用should,ought to,have to填空.

题目

用should,ought to,have to填空.
1.He __ (come)at 4 if the plane arrives on time.
2.I didn't go shopping this morning as I ___ (do) the housework.3.She ___ (come) to see me yesterday,but she forgot.
4.You __ (ask) for permission before you left the table.
5.As they didn't understand,I ___ (explain) everything again.

答案

1 should(ought to) come
2 had to do
3 should have come
4 shoukd have asked
5 had to explain