=>
63. In order not to fall into the swimming-pool and drown, they walled it.
64. Tough measures should be taken by our country to reduce the use of plastic bags, which take hundreds of years to decompose.
65. Banana leaves have been used to pack goods instead of plastic bags by some supermarkets.
66. Was the most valuable painting in the national museum stolen by the thieves?
67. The pollution problems have been discussed by the students since last week.
