They don't know if it ___ tomorrow.If it ___,they will not go to the park

问题描述:

They don't know if it ___ tomorrow.If it ___,they will not go to the park
a.will rain; will rain b.rains; rains
c.rains; will rain d.will rain; rains
为什么选D?两个if引导有何区别?

D
前面的if作“是否"解释,相当于“whether",引导的从句改用什么时态就用什么时态;后面的if作”如果“解释,引导条件状语从句,而条件状语从句中要用一般现在时表将来,所以是rains.