–Mom, may I go swimming with my friends in the river?

   –No, you _________. That’s too dangerous.

    A. won’t           B. don’t           C. needn’t        D. mustn’t

-- May I go out now, Dad?

-- No. You let your mother know first.

　　 A. can B. may C. need D. must

Bill is a lovely boy. He is four years old. There is a park near   1___  house. It is small but beautiful. He  2  with other children in the park every day.
One day, his mother buys new clothes for him.    3   clothes are nice and expensive. Bill is very happy.
“Mum, may I go out     4  play with my friends? I want to show them my    5   clothes.” Asks Bill.
“Yes, please keep your clothes clean.” Says his mother, “I'm going to do some cooking. We will have    6  after your father comes back.”
At about six his father comes back  7   work. Bill goes home for dinner.
“Why do you have so much dirt（泥土）on your  8   ? ” asks his mother when Bill comes into the room..
“Because I have some falls （跌倒）”, answers Bill.
“You mustn't have some falls when you    9   the nice clothes,” says his mother.
“I'm sorry, Mum,”   0   Bill. “But I have no time to take off my clothes when I fall.”

-- May I go out now. Dad?

     -- No. You __    let your mother know first.

  A. can                 B. may                 C. need               D. must