Question

【题目】The little girl cried for several minutes _____ her mother came to comfort her.

A. unless B. while C. once D. before

Answer 1

【答案】D

【解析】句意：小女孩哭了一会儿，妈妈才过来哄她。本句为before引导的时间状语从句，意为“……才” ；while（当……时）引导时间状语从句时，从句谓语动词应为持续性动作；unless（如果不，除非）和once（一旦）均引导条件状语从句。