用方框中所给单词的适当形式填空，每个单词限用一次。

him,   sleep,   unless,    secret,    memorize

小题1:He was so        that he fell asleep soon.
小题2:You won’t get good grades ____________ you study hard.   
小题3:Doing lots of listening practice is one of the ____________ of becoming a good learner.
小题4:_____    all the new words in this unit is a bit difficult for me.
小题5:With his mother’s help, Jim felt good about __________.