what if =what do you do if
如果...,會怎樣?
if 是用來假設(shè)一個狀況:If[狀況],then[后果].
狀況子句要用過去式(did),后果子句用過去未來式(would do).
舉例
問:What if you cloned yourself in the laboratory?
答:Then I would play chess games with my clone.
could 是can的過去式,所以用在狀況子句.
would 是用在后果子句.
舉例
問:What if you could combine a cow and a tiger?
答:Then there would be a new animal specie.