You _____ read a book in the sun—it'll do harm to your eyes．
| A．couldn't | B．wouldn't | C．needn't | D．mustn't |
Never _____ time come back again.
| A．has lost | B．will lose | C．will lost | D．lose |
Can _____ be in the desk _____ you have put my letter？
| A．it；which | B．I；Where | C．you；in which | D．it；that |
Time should be made good use of ____ our lessons well.
| A．learning | B．learned | C．to learn | D．having learned |
---What do you think made the woman so upset？
--- _____ weight.
| A．As she put on | B．Put on |
| C．Putting on | D．Because of putting on |
The research is so designed that once ____ nothing can be done to change it.
| A．begins | B．having begun | C．beginning | D．begun |