Question

有几道英语题不明白，请教。

---- You’ve done this before ,right?----- No, but if we follow the directions, we ___ have any trouble.A. shouldn’t B. couldn’t 答案A，求解释。
You ______scold such a pupil who always keeps silent so seriously that you ____hurt him.
A.mustn't may B.can't must 答案A，求解释。
There is no light on----they ____ be at home.
A.can't B.mustn't 答案A，求解释。
There were already five people in the car,but they managed to take me as well.
It ____ a comfortable jouney.
A.mustn't have been B. couldn't have been 答案B，求解释。
非常感谢，好的再追加！

Answer 1

1、should意思为“应该”句子理解为：如果我们遵照说明，就不应该有什么问题。
2、句子可以理解为：你不应该严厉训斥这个一贯保持沉默的学生，你可能伤到他了。
3、表示推测 一定是用must，一定不是用can not 这句话意思是：灯不亮着，他们一定不在家。