Question

ifyou understand

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

Answer 1

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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