Not everyone has realized what ________important part the balance of ________nature plays in their life.
| A．an；the | B．/；the | C．an；/ | D．the；/ |
The nurse treated the naughty boy very kindly, but her patience _____ at last.
| A．used up | B．gave out |
| C．run out | D．was run out |
You can use a large plastic bottle, _____ cut off, as a pot to grow your plant in.
| A．the top is | B．with its top |
| C．whose top | D．the top of which be |
The boss _____ the workers how to do it, or the accident couldn’t have happened.
| A．can’t have told | B．ought to tell |
| C．could have told | D．mustn’t have told |
The reason _____ their failure you know is ______ they didn’t get fully prepared for the experiment.
| A．why…that | B．that…why |
| C．why…because | D．for…that |
Susan could be a very attractive girl but she ____ no attention to her clothes.
| A．had paid | B．paid | C．pays | D．would pay |