He kept smiling secretly and we were all wondering that made him so happy.
| A．how it did | B．what he did |
| C．how it was | D．what it was |
of the speech, he took out his novel to read.
| A．Tires; tired. | B．Tired; tires |
| C．Tired; tiring | D．Tiring; tired |
At the end of last class, the English teacher requested that the homework this morning.
| A．handed in. | B．be handed in |
| C．would be handed in. | D．had handed in. |
A number of methods been used, but the number of animals still small in the forest.
| A．have; is | B．has; is |
| C．have; are | D．has; are |
If ,the experiment will be successful.
| A．do carefully. | B．did carefully. |
| C．carefully done. | D．doing carefully. |
such heavy pollution already, It may now be too late to clean up the river.
| A．Suffering. | B．Having suffered. | C．To suffer. | D．Suffered. |