【病句诊断】
We will complete the road by the time you come back next year.
【辨析讲解】
句中有个时间状语，by the time you come back next year，这个是指到修好路这个动作到将来的某个时间（也就是明年你回来的那个时间）为止完成。如果要表示在将来某一时间之前已完成的动作，并往往对将来某一时间产生影响。这样就需要用将来完成时，而我们句子句中用的是一般将来时。这个句子是时态错误。
【诊断结果】
We will have completed the road by the time you come back next year.
【举一反三】
By the time you get home I will have cleaned the house from top to bottom. 你到家之前我将把房子彻底打扫一遍。
【考考你】
What will have completed by the end of this year?