Ⅰ.单项选择(每小题1分，共15分)
1．Although they feel tired，______they still go on working.
A．and B．but
C．/ D．so
2．His grandmother is well because she often ______.
A．exercises B．smokes
C．sleeps D．sings
3．—______do they play basketball?
—Every day.
A．How soon B．How much
C．How many D．How often
4．His mother wants him______at home today.
A．stays B．stayed
C．to stay D．staying
