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.