Rewrite the following sentences as required. (根据所给要求，改写下列句子。每空格限填一词。)

1. Jack has to look after her little brother at weekends. (改为一般疑问句)

     _________ Jack _________ to look after her little brother at weekends?

2. Tom checked the mail every day during the summer holidays last year. (改为否定句) 

    Tom _________ _________ the mail every day during the summer holidays last year.

3. We have fine weather today. (改为感叹句) 

    _________ _________ weather we have today!

4. I have always been busy because I have to do a lot of work. (对划线部分提问)

    _________ _________ you always been busy?

5. Sometimes children are so young that they can't tell the bad from the good. (保持句意基本不变)

   Sometimes children are _________ young _________ tell the bad from the good.

6. We will welcome all the visitors when they come to Shanghai in 2010. (改为被动语态) 

    All the visitors will _________ _________ when they come to Shanghai in 2010.