有关状语从句It will be 4 years before he can join the army.为什么只能用before?用that 或when It's 10 years ago +that?那么when呢?又是怎样使用?
网友回答
It's 10 years ago +that表示that引导的句子中的动作发生在10 years ago
It will be 4 years before he can join the army表示join the army这一动作将是4年以后的事情
在这种句式中一般不用when连接