It was terribly windy last night and there was ___18-degree drop in ___ temperature.

题目

It was terribly windy last night and there was ___18-degree drop in ___ temperature.
A.a;/ B./;/ C.an;/ D.an;the

答案

It was terribly windy last night and there was _an_18-degree drop in _x_ temperature.
18 - eighteen ,元音开头,用an
there is a drop in temperature ,是习惯表达.