纠结的语法题 看看啊

That young man has made so much noise that he______not have allowed to attend the concert.
1.could
2.must
3.would
4.should
答案4
为什么 如果用should咋解释啊？

-There were already five people in the car but they managed to take me as well.
-It_____a comfortable journry.
1.can't be
2.shouldn't be
3.must have been
4.couldn't have been
答案4 couldn't表过去否定的猜测 放在这怎么好像解释怪怪的？
为什么？

Joel doesn't regret____even if it might have upset Jennifer.
1.to tell her what he thought
2.to tell her that he thought
3.telling her what he thought
4.telling her that he thought
答案3
这里我觉得应该是Joel不后悔告诉那个女的
最后一道 我觉得应该是那个男人不后悔 后悔不就是用to do了吗
可是为什么用doing

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