(1)连接词+谓语。连接词在从句中作主语。常见的连接词有： who, what, which等。如：
Could you tell me who knows the answer，please?你能告诉我谁知道答案吗?
The small children don't know what is in their stockings.这些小孩子不知道袜子里有什么东西。
I don't know which belongs to my father.
(2)连接词+名词+谓语。连接词在从句中作主语的定语。常见的连接词有：whose, what, which, how many, how much等。如：
He asked whose handwriting was the best in our class.他问我们班上谁的书法最好。
The teacher asked us how many people there were in the room.老师问我们房间里有多少人。
(3)连接词+主语+谓语。连接词在从句中作宾语、状语或表语。常见的`连接词有：who(m), what, which, how many, how much, when, why, how, where, if /whether(在句中不充当任何成分)。如：
Could you tell me what I should do with the money ?你能告诉我我如何处理这笔钱吗?
(4)连接词+名词+主语+谓语。连接词在从句中作宾语或表语的定语。常见的连接词有：what, which, how many, how much, how等。如：
Do you know which class he is in ?你知道他在哪个班吗?
She asked me if I knew whose pen it was.她问我是否知道这是谁的钢笔。
He said that he could finish his work before supper.他说他会在晚饭前完成工作。
I don't know if /whether he still lives here after so many years.
①在具有选择意义，又有or或or not时，尤其是直接与or not连用时，往往用whether(if…or not也可以使用)。如：
Let me know whether /if he will come or not.(=Let me know whethe or not he will come)
I don't know whether/if he does any washing or not.(=I don't know whether or not he does any washing.)
I wonder whether we stay or whether we go.
I'm interested in whether he likes English.我关心的是他是否喜欢英语。
We're thinking about whether we can finish the work on time.
I worry about whether I hurt her feelings.我担心是否伤了她的感情。
He hasn't decided whether to visit the old man.他尚未决定是否拜访那位老人。
I don't know whether to go.我不知去否。
He hasn't decided whether to go by bus or by train.他还未决定是乘公共汽车去还是坐火车去。
Whether this is true or not, I can't say.这是否真的我说不上来。
Whether she will come or not is still a question.她是否能来还是个问题。
The question is whether we can catch the bus.问题是我们能否赶上公共汽车。
Please let me know if you like the book.可理解为：a. Please let me know whether you like the book.请告诉我你是否喜欢这本书。B. If you like the book, please let me know.你如果喜欢这本书，请告诉我。
Could you tell me why you were late for the meeting this morning?
疑问词是疑问代词“who, whom, what, which, whose”和疑问副词“when, where, how, why”。此外，连接词“whether”也适用。
When to hold the meeting has not yet been decided.
Where to live is a problem.
How to cope with the rising cost of living becomes a daily discussiontopic.
We must know what to say at a meeting.
He could not tell whom to trust.
Do you know how to play bridge?
The problem is where to find the financial aid.
The question is who to elect.
Tom had no idea which book to read first.
Do you have a rough impression how to do it?
Jim is not sure whose to choose.
Mary and John are not certain whether to get married or not.
适用于“疑问词+不定式动词”的动词包括：“know, see, decide, tell, ask, consider, discover,explain, forget, guess, hear, imagine, inquire, learn, remember, think, wonder,understand”等。
I could not decide which dictonary to buy./ I could not decide whichdictionary I should buy.
Jack did not know where to find such a good teacher./ Jack did not knowwhere he could find such a good teacher.
有些动词，如“ask, show, tell, advise, inform,teach”等，可以先有个宾语，然后才接着加上适当的“疑问词+不定式动词” 结构。例如：
The chief technician showed the apprentice how to repair the machine.
Have you told him where to get the application form?
现在进行时表示此时此刻正在发生的事情。常与now，at the moment，look，listen等词连用。
The little boy is watching TV now.
Listen!She is playing the guitar in the next room.
否定式：am/is/are not +doing(现在分词)
一般疑问式：Am/Is/Are + 主语 +doing(现在分词)+ 其他
They’re having a meeting now.
They aren't having a meeting now.
Are they having a meeting now?
What are they doing now?