if you this experiment,you will understand the theory better.

题目

if you this experiment,you will understand the theory better.
答案是have done,为什么呢?

答案

if引导条件状语从句,某事很可能发生,条件是可能存在的,主句中某种情况发生的概率也是很高的.
if从句用现在完成时,主句用一般将来时.如.
If you "have finished" dinner,I’ll ask the waiter for the bill.
如果你吃完了,我就叫服务生来算账
所以题目填have done,
if you "have done"this experiment,you will understand the theory better.
如果你做完这个实验,你就会更好地理解这个理论.
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