什么时候使用should be?

特殊的虚拟语气词：should
1） It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形， should 可省略。
句型：
(1)suggested
It is (2)important that…+ (should) do
(3) a pity
(1)suggested, ordered, proposed, required, demanded, requested, insisted； + (should) do
(2)important, necessary, natural, strange
a pity, a shame, no wonder
(3)It is suggested that we (should) hold a meeting next week.
It is necessary that he (should) come to our meeting tomorrow.
2）在宾语从句中的应用
在表示命令、建议、要求等一类动词后面的从句中。
order, suggest, propose, require, demand, request, insist, command, insist + (should) do
I suggest that we (should) hold a meeting next week.
He insisted that he (should ) be sent there.
2．should的用法
1）表示“允诺”。
Mother told Tom he should have such a book tomorrow．妈妈告诉汤姆明天他就可得到这样一本书。
You should have a ticket as soon as I get some．我一弄到票就给你一张。
2）表示“强制、命令、威胁”，用于二、三人称的陈述句中。
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