The scientist, who space all his life, is retiring next week.
| A．had explored |
| B．is exploring |
| C．has been exploring |
| D．explored |
New medicines and instruments ______ every day to extend life.
| A．develop | B．are being developed |
| C．are developing | D．have developed |
A red sky in the morning ______ to be a sign of bad weather.
| A．says | B．is saying |
| C．has said | D．is said |
Hundreds of jobs _______ if the factory closes.
| A．lose | B．will be lost |
| C．are lost | D．will lose |
“Look！ Everything here is under construction.” “What is the small building that ______for？”
| A．is being building | B．has been built |
| C．is built | D．is being built |
He kept a little notebook, in which ______ the names and addresses of his friends.
| A．wrote | B．was writing |
| C．was written | D．were written |