The question occurred to me ______ we were to get the machine needed.
| A．that | B．what | C．why | D．where |
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 |
We have the most population in the world, and most of it _______ farmers.
| A．to be | B．is | C．are | D．being |