Seeing the big crowd coming towards him, he started to run down the hill, but ______ and went down on his hands and knees in the melting snow.
| A．slipped | B．skied | C．signalled | D．sank |
Plastic parts can __________ metal ones in many machines. But they don't last long.
| A．substitute with |
| B．be replaced with |
| C．take the place of |
| D．in place of |
Large quantities of china made in Dehua __________ to the US and Europe.
| A．has exported |
| B．will export |
| C．is exported |
| D．are exported |
-It's said that scientists have made __________ big breakthrough in the cancer treatment.
-If so, many people can have been brought back to __________ life ！
| A．a; / |
| B．/；a |
| C．the; the |
| D．a; the |
The police __________ searching for the murderer everywhere when he suddenly appeared in a theatre.
| A．is |
| B．was |
| C．are |
| D．were |
Experiments of this kind __________ in both the U. S. and Europe well before the Second World War started.
| A．have conducted |
| B．have been conducted |
| C．had conducted |
| D．had been conducted |