81. I think the dress is in style.　 (改为否定句)

I 　　　　　think the dress 　　　　　in style.

80. There will be less pollution in the future.　 (改为反意疑问句)

There will be less pollution in the future， 　　　　　　　　　　？

79. We don’t know when we will leave the city.　 (改为同义句)

We don’t know 　　　　　　　　　　　　　　　the city.

78. The girl was shopping when the accident happened．　 (对划线部分提问)

　 　　　　　　　　　　the girl 　　　　　when the accident happened?

77. “Could I copy your homework?” He asked me.　 (改为间接引语)

He asked me 　　　　　　　　　　　　　　　copy　　　　 　homework.

76. The yellow pants are 　　　　　　(cheap) of all.

75. I like swimming because it can make me 　　　　　　(keep) fit.

74. The children enjoyed 　　　　　　(they) on the Great Wall.

73. My parents 　　　　　　(buy) me a new bicycle yesterday.

72. The boys 　　　　　　(play) soccer when I got there.