I was bored staying here for years, ________ whether I should try someplace different.
| A．wondered | B．to wonder |
| C．wondering | D．wonder |
Only after her mother came to help her for the first few months ______ to begin her project.
| A．did she allow | B．had she allowed |
| C．was she allowed | D．is she allowed |
Thanks to Dr Yuan’s research, the UN has more tools in the battle to rid the world _____ hunger.
| A．of | B．on | C．off | D．at |
______ is even more important is that the earth cooled down, water began to appear on its surface.
| A．When | B．That | C．Which | D．What |
Jane _____ these families of chimps for many years and helped people understand how much they behave like humans.
| A．had studied | B．studied | C．studies | D．has studied |
It is so wet there _____ the trees are extremely tall, some measuring over 90 meters.
| A．what | B．which | C．that | D．why |