Expression: be good at

[Melody]

English Grammar Tests, Elementary Level

ESL/EFL Test #91 "Using Prepositions", question 5

To get a job as a secretary, you must be good ......... typing and answering phones.

(a) for
(b) at
(c) with
(d) about

English Grammar Tests, Elementary Level

ESL/EFL Test #91 "Using Prepositions", answer 5

To get a job as a secretary, you must be good at typing and answering phones.

Correct answer: (b) at
_________________________

I want to get an explanation.

Melody

[Mister Micawber]

.
The grammatical structure is good/bad/poor/etc at:

He is good at math; she was poor at skiiing until she took lessons.

The other prepositions offered in this test question are incorrect.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mr. Micawber