Question

Someone called me up in the middle of the night, but they hung up ________I could answer the phone.

A．since

B．until

C．before

D．as

Answer 1

C

试题分析：句意：有人在深夜给我打电话，但是我还没接听电话，他们就挂了。考查时间状语从句，since自从,until直到,before在……之前,as当……时候，由题意很容易选C。
考点: 考查状语从句的用法。