I wany to know后面是加what is he doing 还是what he is doing?为什么？

I wany to know后面是加what is he doing 还是what he is doing?为什么？ I do not know what to reply .请问为什么what 后面要加一个to ,是词组,还是什么语法, I don't know when to leave为什么when后面要加to I don't know when to leave为什么when后面要加to. i don't know where to put 后面能加 it 形式主语后面加什么I know it is useful to learn a language well I wany to book a return ticket form GuangZhou to BeiJing的意思 i donnot know what to do with it do you know how to deal with 为什么后一句反而不加 it 前面know后面跟的不是宾语从句吗?从句中有了宾语前面还加what儿后面前面用的是副词反而不加it这是怎么回事 1.----I don`t know ____Tom will come this afternoon.----I`m sure he won`t.He has后面还有1.----I don`t know ____Tom will come this afternoon.----I`m sure he won`t.He has to look after his sick sister at home today.A.where B.why C.if D.that2.----Wh I know it is not easy for you to achieve.这句后面要不要加it 为什么 to know后面可以直接加名词么 英语语法之to的定义?“I want know .” 与“I want to know .” 有什么不一样么?不就是少了个“to”么?是不是“want ”是及物动词后面能直接跟宾语,而不加“to”也可以?又比如“I go to school”中“go When I was lonely,painful time,I always want you,I would like to know what you're doing,wh是什When I was lonely,painful time,I always want you,I would like to know what you're doing,what busy,so I feel more enriched是什么意思? I want (to)know 这里的know 是名词还是动词 我知道名词不用加to i don't know what to say.可不可以说i don't know say what有没有用say what的情况I don't know what do you say.为什么what后面要加do? 必须加 it 的 动词哪些动词后面必须加 it 比如 I don't know how to say it.越多越好我是问哪些单词后面必须加it,而我们平时没有太注意这些单词，像 “I don't know how to say it.很多人会说 “I don't know I am used to travelling by air.语法 to 后面都是加原型,为什么这个是加ing形式? i i wang to go i want to know 有这句歌词的是那首歌的啊?女的唱的,后面好似摇滚的!