Question

The children were worried about their mother. They didn’t go to bed ___  their mother came back..

A．when

B．while

C．until

D．after

Answer 1

C

解析试题分析：句意：孩子们担心他们的妈妈，直到妈妈回来后他们才上床睡觉。not…until…直到……时候才……。故选C。
考点：考查连词。