—What happened to Tom?
—He ______ his leg while playing football with his classmates.
| A．had broken | B．has broken | C．broke | D．was breaking |
Don’t forget to bring a dictionary next class.
___. I didn’t catch what you said.
| A．Never mind | B．I beg your pardon |
| C．That’s right | D．I’m not sure |
Carbon dioxide ___ from burning fuels is the most common of the so-called greenhouse gases.
| A．producing | B．having been produced |
| C．to be produced | D．produced |
Father finally came back home, which I ___ forward it.
| A．had been looking | B．have been looking |
| C．looked | D．have looked |
. Information has been put forward ___ more middle school graduates will be admitted into universities.
| A．while | B．that |
| C．when | D．as |
Determination is a kind of basic quality and this is ___ it takes to do jobs well.
| A．what | B．that |
| C．which | D．who |