1.shall 用于第一、三人稱的疑問句,表示征詢對方意見和請示.多用疑問句
Shall he come in or wait outside?
Shall we make it next Saturday?
2.shall表示警告和強烈的建議：
The law of Venice says that if anyone tries to kill or murder any citizen of Venice,everything that he owns shall be taken away from him
The interest shall be divided into five parts,according to the agreement made by both sides.,declared the judge.
3.should 用于對將來進行虛擬的條件句中Should it rain tomorrow,the sports meeting will be called off.
4.用于if和in case 之后,表示某事不太可能發(fā)生,常譯為“萬一”,“以防……”.
If you should change your mind,do let me know.
Take your umbrella with you,in case it should rain.
5.用在名詞性從句中,表示驚異、意外等情緒,常譯為“竟然”.
（1） You can't imagine that a well behaved gentleman should be so rude to a lady.
（2） Well,I could never imagine an honest boy like John,should cheat in the exam!