We can not figure out quite a number of insects, birds, and animals are dying out.
| A．that |
| B．as |
| C．why |
| D．when |
Each of the students, working hard at his or her lessons,___to go to university.”“So do I.”
| A．hope | B．hopes | C．hoping | D．hoped |
He told me the news_____, believe it or not, he had earned $1 000 in a single day.
| A．that | B．which | C．as | D．because |
In that month, he earned as much as, if ____ than, $40 000.
| A．no more | B．not more | C．no much | D．not much |
The research is so designed that once _____ nothing can be done to change it.
| A．begins | B．having begun | C．beginning | D．begun |
If _____ carefully, the experiment will be successful.
| A．do | B．does | C．done | D．doing |