B）用括号内所给单词的适当形式填空。
【小题1】Why don’t you __________（sit）down and communicate with your friends?
【小题2】While Mary __________（sleep）, Jenny was helping her mother do housework.
【小题3】The __________（early）kids learn to be independent, the better it is for their future.
【小题4】The Caspian Sea is __________（deep）of all the salt lakes.
【小题5】My brother __________（have）a train and railway set since his fourth birthday.