问题
选择题
The task _______ by the time you come back.
A．has been completed
B．will have been completed
C．will complete
D．has completed
答案
答案：B
此题考查时间状语从句。by the time+一般现在时态，主句应用将来完成时态，by the time+一般过去时态，主句应用过去完成时态，题中by the time后面是一般现在时态you come back，故选B，若掌握by the time的用法，就不难了。