问题
选择题
— Mom, my classmates are playing outside. Can I join them?
— Not until your homework .
A．finishes
B．is finished
C．finished
D．was finished
答案
答案：B
题目分析：句意：妈妈，我的同学在外面玩，我可以加入他们吗？直到你的作业完成了你才能去。动作的承受者作主语，用被动语态。其结构是，主语+be+done.在时间状语从句中主句用将来时态从句用一般现在时。根据句意，故选B。