be动词什么时候后面加to?

什么时候不加?

be to do 表示将要做某事可以用,且表示1)按计划或安排要做的事 2)表示指令,相当于should,ought to, must, have to, This meicine is to be taken three times a day. 3) 表示 想,打算,相当于intend to , want to If you are to listen to the consert, you'd better hurry up.
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第1个回答  2011-04-16
用动词不定式作表语时;
be to do sth表将来时可以用;本回答被网友采纳
第2个回答  2011-04-16
My job is to...
My ambition is to...
My hope is to...
"...是 to do"