Come and see me whenever ________.
A. you are convenient B. you will be convenient
The difficulty which we had _______ with the local people has now been removed·
| A．communication | B．to communicate |
| C．communicated | D．communicating |
The surface of the table ______ smooth enough．
| A．hash’t felt | B．isn’t feeling | C．doesn’t feel | D．isn’t felt |
At last，we found ourselves in a pleasant park ________trees providing shade(荫凉)and sat down to eat our picnic lunch．
| A．for | B．from | C．of | D．with |
.Manufacturers should have professional productivity and technical knowledge to ______ the quality of the products.
| A．predict | B．promise | C．guarantee | D．determine |
.It was in the 1990s _______ we were working together ____ we made friends with each other.
| A．that; when | B．when; that | C．that; that | D．when; when |