They are putting too much carbon dioxide into the atmosphere, ______ prevents heat from escaping from the earth into space.
| A．what | B．that | C．which | D．who |
He’s rather walk than ___ a bus in the rush hour.
| A．take | B．to take | C．taking | D．took |
I’m quite familiar ___ the writer who wrote these songs.
| A．to | B．for | C．with | D．at |
We made plans for a visit but _____ difficulties with the car prevented it.
| A．consequent | B．subordinate |
| C．substantial | D．subsequent |
He didn't _____ what I read because his mind was on something else.
| A．hold on | B．catch on | C．take in | D．get over |
Scientists have to work hard to keep _____ with modern discoveries and developments.
| A．company | B．track | C．touch | D．pace |