Because of the bad weather,many of Europe's airports have shut and passengers had to stay in congested airspace.
问题描述：
Because of the bad weather,many of Europe's airports have shut and passengers had to stay in congested airspace.
由于天气问题,许多欧洲机场关闭,旅客不得不滞留在拥挤的空间.
请问这个句子中的时态,为什么前面是现在完成时have shut,而后面是一般过去式had to stay,
答
现在完成时,have done,表示完成,had to,have to的过去式,前面是由于许多欧洲机场关闭,所以旅客不得不滞留在拥挤的空间,have shut 的时间发生在stay前,所以为什么前面是现在完成时have shut,而后面是一般过去式had to stay