虚拟语气的三种时态（虚拟语气---------be-型虚拟式）

be-型虚拟式是以动词原形表示的，即不管主语是什么人称，动词一律用原型，如 i go,you go 或者I be,you be ,he be.

1:用于表示命令、决定、建议等词语之后的that-分句中

be-型虚拟式的这一用法又有以下三种情况

a:用在decide, decree, demand, insist, move(提议），order, prefer, propose, recommend, request, require, suggest, vote等动词之后的that-分句中。

eg:

He ordered that all the books be sent at once.

We propose that somebody neutral take the chair(担任主席）。

She insisted that she go to the south for her holiday.

The doctor insisted that he not eat meat .

b:用在advisable, appropriate, desirable ,essential, fitting, imperative, important ,impossible, necessary, obligatory, proper等形容词之后的that-分句中。

eg:

It is essential that all the facts be examined first.

It is necessary that he come back without delay.

I thought it advisable that an armed guard stand in readiness.

It was appropriate that this tax be abolished.

c:用在decision, decree, demand,instruction, order ,requirement, resolution等名词后的that-分句中。

eg:

The board(理事会）has given instructions that the agent fly to Boston.

We were faced with the demand that this tax be abolished.

Your advice that she wait till next week is reasonable.

在这一用法中be-型虚拟式能与 should 不定式交替使用，也能与to -不定式交替使用。

2:用于由 if ,though等连词引导的分句中

be-型虚拟式能用于由 if, though,whatever, lest, so long as等引导的分句中表示推测、防备等含义。

eg:

If he be found guilty,John shall have the right of appeal.

If the rumour be true ,everything is possible.

Though everyone desert you ,i will not .

Whatever be his defense we can not tolerate this disloyalty.

So long as a volume hold together , i am not disturbed as to its outer appearance.

Whether she be right or wrong ,she will have my unswerving support.

3:用于某些公式化语句中

be-型虚拟式用于某些公式化语句中可表示祝愿、诅咒、禁止等意义。

eg:

Long live the People's Republic of China.

God bless you !

God damn you !(该死的！）

So be it .(但愿如此、就这样吧）

Far be it from me to (我极不愿）spoil the fun.

He will remain here if need be .

Home is home ,be it ever so homely.