No chicken or duck ______ in the supermarket since the first case of H7N9 was reported dead.
| A．has been sold | B．was sold | C．is sold | D．are sold |
—Car prices have been going down sharply in the last 20 years.
—It's not surprising because the law of market ________ the price of a product.
| A．is controlling | B．controls |
| C．has controlled | D．controlled |
Is he the only one of the students who ________ here just now?
| A．is | B．are | C．was | D．were |
We ________ jump to conclusions before we have all the facts.
| A．couldn't | B．mightn't | C．shouldn't | D．mustn't |
It was several years ________ I realized ________ David had lied to me.
| A．when; that | B．that; when |
| C．before; that | D．until; why |
The project will help people understand the many threats to the natural environment ________ endangered plants and animals live.
| A．which | B．when | C．where | D．that |