New technology ______ to make sure that the cars, taxis, buses and trains we use ______ the air.
| A．is used; not to pollute | B．has used; is not polluted |
| C．is being used; do not pollute | D．has been used; to pollute |
--- The conflict between North and South Korea calls for talks to solve the problem.
---Quite right. I would rather the UN_______ something immediately.
| A．would do | B．does | C．did | D．will do |
With such an ecological variety, amazing natural beauty, and so much to do, it's _______ that the falls are a wonder.
| A．no doubt | B．no way | C．no wonder | D．no problem |
Having finished the work, _______.
| A．it was almost six o’clock |
| B．supper was ready |
| C．a postman came and delivered some letters. |
| D．we had a rest and then had supper |
---When was Tom bitten by a snake?
---It was on a Sunday _______ he was taking a trip to the mountainous area.
| A．that | B．when | C．which | D．where. |
When this new kind of virus broke out at first in Mexico, no one had the least idea that it would _______ so rapidly throughout the world.
| A．export | B．spread | C．expand | D．deliver |