American Diploma · ACT · English: Usage

Idioms and Prepositions

The right small word after capable, interested, consist, prefer and dozens more — a grouped table of 50 ACT idioms, meaning-dependent prepositions and gerund vs infinitive, with a 10-question ACT-style quiz.

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An idiom is a fixed way of saying something. English decides that we are *interested in* something but *capable of* something, that we *decide to go* but *avoid going*. There is no logic rule that tells you which small word is right — native speakers just know it. For students who learned English as a second language, this makes idiom questions some of the hardest on the ACT. The good news: the same few dozen combinations appear again and again. This lesson gives you the method, a large grouped table to learn, and the gerund-vs-infinitive rules.

What this question type tests

Idiom questions are usage and word-choice questions. They belong to the ACT English categories Conventions of Standard English (38–43% of the 40 scored English questions) and Knowledge of Language (18–23%), which is about precise and appropriate wording. On the page they look like any other ACT English item: a short underlined portion and four choices, usually with NO CHANGE first, often with no stem.

You can recognise them with a vertical scan: the choices are almost identical and only one small word changes (of / for / in / to / with / on), or the verb form after a word changes (to design / designing / of designing).

The method

Find the "anchor" word just before the preposition: the adjective, verb or noun that controls it (capable, consist, responsible, interest).
Say each choice silently with the anchor word, ignoring the rest of the sentence: "capable of", "capable to", "capable for". The standard pair usually stands out.
Check what follows the preposition. After a preposition, a verb must be in the -ing form: capable of designing, interested in learning, insist on paying.
If two choices both sound fine, check the meaning. Some anchors take different prepositions for different meanings (agree with a person / agree to a plan).
If you still cannot decide, eliminate any choice that is longer or adds words — idiom questions rarely reward extra words.

الإيديوم مفيهوش قاعدة… احفظه

الـ idiom معناه كلمتين بييجوا مع بعض دايمًا زي capable of و interested in و consist of. مفيش منطق، لازم تحفظ. في الامتحان: شيل باقي الجملة وقول الكلمة مع الحرف بس (capable of ولا capable to؟). وخلي بالك: أي فعل بعد حرف جر لازم ييجي ing زي interested in learning.

The big table: 50 common ACT idioms

Learn these in groups. The right-hand column shows the mistake students most often make.

Group A — adjective + preposition

✓ Standard	✗ Common error	✓ Example
capable of (+ -ing)	capable to do	capable of lifting ten tonnes
interested in	interested about / for	interested in robotics
different from	different with / of	Life in the village is different from life in Cairo.
similar to	similar with / as	similar to the old design
responsible for	responsible of	responsible for the budget
aware of	aware about	aware of the risk
afraid of	afraid from	afraid of heights
proud of	proud with / for	proud of her daughter
familiar with	familiar to (a person)	familiar with the software
famous for	famous with / of	famous for its dates
typical of	typical to / for	typical of desert plants
consistent with	consistent to	consistent with the evidence
essential to / for	essential in	essential to survival
independent of	independent from (avoid)	independent of the government
superior / inferior to	superior than	superior to the earlier model
fond of	fond with	fond of music

Group B — verb + preposition

✓ Standard	✗ Common error	✓ Example
consist of	consist from / in	The team consists of six engineers.
depend / rely on	depend of / rely to	Farmers depend on the river.
insist on (+ -ing)	insist to go	She insisted on paying.
succeed in (+ -ing)	succeed to do	He succeeded in finishing early.
prevent / prohibit / stop … from (+ -ing)	prevent him to go	The rain prevented us from leaving.
prefer X to Y	prefer X than Y	I prefer tea to coffee.
contribute to	contribute in	contributed to the project
focus / concentrate on	focus in / at	focus on one goal
apologise for (something) / to (someone)	apologise about	apologised to the teacher for the delay
comply with	comply to	comply with the rules
result in (cause) / result from (be caused by)	result to	Heavy rain resulted in floods. Floods resulted from heavy rain.
object to (+ -ing)	object against	She objected to waiting.
participate in	participate at / on	participate in the competition
regard / see / view X as Y	regard X to be Y	They regarded him as a hero.
protect … from / against	protect of	protect plants from frost
dream of / about	dream for	dreamed of becoming a pilot

Group C — noun + preposition

✓ Standard	✗ Common error	✓ Example
interest in	interest for / about	an interest in history
respect for	respect to (meaning admiration)	respect for her elders
the reason for / the reason is that	the reason of / the reason is because	The reason for the delay was the storm. The reason is that the road closed.
a solution to	a solution for / of	a solution to the problem
access to	access for	access to clean water
an increase / a decrease in	an increase of (when naming the thing)	an increase in prices
a demand for	a demand of	a demand for electric cars

Group D — fixed expressions and paired words

✓ Standard	✗ Common error
not only X but also Y	not only X and also Y
either X or Y / neither X nor Y	either X nor Y / neither X or Y
both X and Y	both X as well as Y
between X and Y	between X to Y / between X or Y
from X to Y	from X until Y (in ranges)
so + adj. + that / such a + noun + that	so … as / such … as (for result)
as + adj. + as	as … than
in contrast to / in contrast with	in contrast of
according to	according with (in this meaning)
in charge of	in charge for
on the other hand	in the other hand
in accordance with	in accordance to
try to (formal)	try and (casual)
could have / should have / would have	could of / should of

Safe ACT choices for a few disputed idioms: *different from* is always correct (avoid *different than* in ACT essays); *regard X as Y* (not *regard X to be Y*); *independent of*.

When the preposition changes the meaning

For some anchor words, more than one preposition is standard, but each one means something different. Here the method is meaning first.

Anchor	Preposition → meaning	✓ Example
agree	with a person / an opinion · to a proposal · on a decision both sides make	I agree with you. They agreed to the plan. We agreed on a date.
compare	to = say one thing is like another · with = examine similarities and differences (careful writing keeps this difference)	She compared the city to a beehive. We compared this year's results with last year's.
differ	from = be unlike · with = disagree with a person	My answer differs from yours. I differ with you on this point.
angry	with / at a person · about a situation	angry with his brother about the noise
result	in = cause · from = be caused by	Smoking results in illness. Illness results from smoking.

Gerund or infinitive?

A gerund is verb + -ing used as a noun (swimming, designing). An infinitive is *to* + verb (to swim, to design). Some verbs must be followed by one form, some by the other. The ACT tests the most common ones.

Verb + to + verb (infinitive)	Verb + -ing (gerund)
decide, plan, hope, expect, want, intend	enjoy, avoid, finish, keep, mind, quit
agree, refuse, promise, offer, threaten	consider, suggest, recommend, risk, imagine
manage, fail, attempt, try, tend, seem	admit, deny, delay, postpone, practise, miss
afford, deserve, learn, need, prepare	appreciate, resist, discuss, involve, mention
✓ They decided to build a bridge. ✗ decided building	✓ She avoided answering. ✗ avoided to answer

After any preposition → -ing: ✓ interested in learning, ✓ capable of designing, ✓ before leaving, ✓ instead of waiting. ✗ interested in to learn.
"to" can be a preposition, not part of an infinitive. Then it is followed by -ing: ✓ look forward to seeing you, ✓ be used to working late, ✓ object to paying, ✓ committed / dedicated to protecting, ✓ the key to solving. ✗ look forward to see you. Test: if you can put a noun after *to* (look forward to the holiday), *to* is a preposition → use -ing.
Verbs that change meaning: *stop* — ✓ He stopped smoking (quit) / He stopped to smoke (paused in order to smoke). *remember / forget* — ✓ I remember locking the door (I did it earlier) / Remember to lock the door (a task for later).
Parallelism after these verbs: keep both items in the same form: ✓ She enjoys reading and writing. ✗ She enjoys reading and to write.

to ولا ing؟

أفعال زي decide و plan و hope و agree و refuse و manage بعدها to + فعل: decided to build. وأفعال زي enjoy و avoid و finish و consider و suggest بعدها ing: avoided answering. وأي حرف جر (in, of, on, for) بعده ing. خلي بالك من look forward to و be used to: الـ to هنا حرف جر، فنقول look forward to seeing.

Worked examples

Each example is a sentence from an ACT-style essay. The underlined portion is shown in bold.

Worked example 1 — adjective + preposition. "Many young architects in Egypt are capable to design buildings that stay cool without air conditioning."