it is a must for us to have a good command of the english lauagne.这里为什么加a啊

Water is important for us,so we must( )it.Water is important for us,so we must( )it.A.(take)B.(save)C.(eat)D.(live) it is a must for us to have a good command of the english lauagne.这里为什么加a啊 it is difficult a book for us you must keep-------(fit)because it is important for all of us it is good for us Life is not easy for any of us.We must work,and above all we must believe in ourselves .We must believe that each o ne of us is able to do something well,a nd that,when we discover what this so mething is,we must work hard at it unt il we succeed翻 is it good for for us or bad for us They ……for us .but it is more likely that they have gone without us .A.must be waiting.B can be waiting.C may be waiting.D are waiting. ____ no need for us to discuss it again.A There is B It is 为什么 用must或have to来代替括号里的词组1.（It will be necessary for you to)see a doctor.2.(Is it necessary for you to)make so much noise?3.She said (it would be necessary for us to)stay here.4.(It is necessary for me to)have some help.5.(It was It is important ( )us to keep healthy 中间甜什么 keeping healthy is important ( )us主语是it时什么时候用(for )us 和 (to )us如It is a mystery to me为什么不用(for )us It is diffcult for us stand up it is good for us study english I think it is bad for us It is necessary for us to master a foreign language.请问for us在句中做什么成分? It is time____go to work.A.of us to B.for we to C.we will D.for us to it time for ____?117.Is it time for ____?A.us to play chessB.us for playing chessC.we for playing chess选那个 Is it polite for us to ask about a girl is age?