We can’t figure out ______ quite a number of insects and birds are dying out．
| A．that | B．as | C．why | D．when |
.
--- Are you going to stay overnight?
--- Not__________it’s really necessary.
| A．if | B．unless | C．until | D．since |
.
A volunteer is a person willing to help others, one who offers to do something without__________.
| A．paying | B．paid | C．being paid | D．to pay |
.
The program “Hear with Yushu, Love Has No borders” told touching stories about rescue volunteers, whose brave deeds__________never be forgotten.
| A．can | B．may | C．need | D．must |
.
We didn’t tell Susan about our plan__________upsetting her.
| A．for fear of | B．regardless of | C．in face of | D．instead of |
.
Though the teacher had tried to make the problem easy__________, still Lily and her partner were at a loss.
| A．understood | B．understanding | C．to understand | D．to be understood |