Look!They ________ in the river．

1. A.
   swim
2. B.
   are swimming
3. C.
   are swiming
4. D.
   to swim

Look at those boys and girls. They are having a good ________.

1. A.
   time
2. B.
   idea
3. C.
   park
4. D.
   swim

—Look，how happily the boys are swimming in the pool!

—How long ________ they ________?

—For about an hour．

A．have，been swimming                             B．have，swum

C．do，swim                                                 D．have，be swimming

Look at those boys and girls. They are having a good ________.

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Look at those boys and girls. They are having a good ________.

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