This nationwide smog should serve as a reminder to all, indicating a high time that we ______ on what we've done to the environment.
| A．have reflected | B．are reflecting | C．will reflect | D．reflected |
Because the shop_____, all the T-shirts are sold at half price.
| A．has closed down | B．closed down | C．is closing down | D．had closed down |
Leaving behind family members, these farmers are strangers to the cities ______ they work.
| A．in that | B．at which | C．where | D．which |
Last week, only two people came to look at the house, _______ wanted to buy it.
| A．none of them | B．both of them |
| C．none of whom | D．neither of whom |
That’s the new machine ________ parts are too small to be seen.（）
| A．that | B．which | C．whose | D．What |
Is this research center _____you saw the modern equipment last year?
| A．which | B．that | C．the one where | D．the one that |