It's really very dangerous. One more step，________the baby will fall into the well.
| A．or |
| B．so |
| C．but |
| D．and |
Some students even have no idea of they are studying, so they waste much time playing.
| A．what | B．when | C．why | D．where |
If you ________ smoke in the room, please keep the windows open.
| A．should | B．may | C．shall | D．must |
From the top of the tower, people can see at least ________ distance of 10 kilometers on ________ clear day.
| A．a; the | B．不填； a | C．a; a | D．the; the |
A number of high buildings have arisen ______ there was nothing a year ago but ruins.
| A．where | B．when | C．before | D．until |
I’d like to go to Tommy’s birthday party this evening, but I _____ just _____ from the flu.
| A．am---recovering | B．will--- recover |
| C．was--- recovering | D．had --- recovered |