–We should do what we can _____ the endangered animals.`
--Yes, it’s duty_____ them.
| A．save, to protect | B．save, protect |
| C．to save, protect | D．to save, to protect |
The first thing ______ we should do is to tell him the mews.
| A．who | B．which | C．that | D．whom |
What way can you think of ______ the mice in the room?
| A．how to kill | B．to kill | C．killing | D．killed |
Yuan Longping, a great person in China, _____as “father of hybrid rice”
| A．is regarded | B．has regarded | C．is regarding | D．regards |
______ the work is difficult, all the workers are keeping on working .
| A．But | B．Although | C．And | D．So |
Tom often makes his brother___but yesterday he was made___ by his brother.
| A．cry; to cry | B．to cry; cry | C．cry; cry | D．to cry; to cry |