The ground is slippery. Hold onto the rope and don’t ____.
| A．put off | B．turn up | C．let go | D．take apart |
After years of research, he found the key ____ differences between species.
| A．to explain | B．to explaining | C．of explaining | D．explaining |
--- Do you know Anna’s telephone number?
--- ______. As a matter of fact, I don’t know any Anna, either.
| A．I think so | B．I hope so | C．I’d rather not | D．I am afraid not |
I have two elder brothers, ____ in the army for ten years.
| A．the elder of whom served | B．the older having served |
| C．the older of which served | D．the elder one has served |
Everyone had an application form in his hand, but no one knew which office ___.
| A．to send it to | B．to send it | C．to be sent to | D．to have it sent |
--- Come on, please give me some ideas about the project.
---Sorry. With so much work ____ my mind, l almost break down..
| A．filled | B．filling | C．to fill | D．being filled |