66. the piano was so heavy that nobody could move it

67. the piano was not light to move

68. It is such a complicated situation that I can't explan

69. It is too complicated for me to explan

70. It is not simple enough for me to explan.

XIV.

71. The wall was cleaned before they painted it

72. John is usually visitted  by Mr.Cole at the weekend

73. Trees used to be planted by Nam in the spring 

74. Is the work finished in time?

75.His sister was made to sweep the floor

76. be his children have to fetched every day?

77. I haven't been given the detailed contract.

78.My mother has been seen cook for two hour.

66+67) The piano was so heavy that nobody could move it.

The piano wasn't light enough for anybody to move.

68+69) It is such a complicated situation that I can't explain.

The situation is too complicated for me to explain.

The situation isn't simple enough for me to explain.

70) The wall was cleaned before it was painted (before they painted it). 

71) John is usually visited by Mr.Cole at the weekend.

72) The keys have been found in the drawer.

73) Trees used to be planted in the spring by Nam.

74) Is the work finished in time?

75) He made the floor swept by his sister.

76) Are Mr.Jim's children have to be fetched by him every day.

77) The detailed contract hasn't been given to me.

I haven't been given the detailed contract.

78) My mother has been seen cooking for two hours by my sister.

79) Have you been bought a present by your parents?

Has a present been bought for you by your parents?