China’s new food law provides for a food recall(召回) system__________ producers have to stop production if their food isn't up to standards.
| A．where | B．that | C．when | D．which |
Facing the ________situation, the boss of the company looked____
| A．puzzling, puzzled | B．puzzling, puzzling |
| C．puzzled, puzzled | D．puzzled, puzzling |
As we all know, _________ car is becoming _________ popular way of transportation in big cities.
| A．the; a | B．a; / | C．the; / | D．a; the |
—Tom, you are smoking again?
—______? It’s none of your business.
| A．So what | B．How come |
| C．Why not | D．What for |
It was too hard for the firefighters to get close to the burning building. All their attempts to rescue the people trapped were ______.
| A．in place | B．in return |
| C．in vain | D．in danger |
When first _______ to the market, the products didn’t attract much attention.
| A．introducing | B．introduced |
| C．was introduced | D．being introduced |