The nationwide smog serves as a constant reminder, indicating that it’s high time we ______ on ourselves.
| A．would reflect | B．have reflected |
| C．are reflecting | D．reflected |
Bad habits, _______ formed, are difficult, and sometimes impossible to shake off.
| A．before | B．once | C．until | D．unless |
I will never know what was on his mind at the time, nor will _______.
| A．anyone | B．anyone else |
| C．everyone | D．no one else |
A small plane crashed into a hillside five miles east of the city, _______ all four people on board.
| A．killed | B．to kill | C．kills | D．killing |
—Jenny, it won’t be long before I receive the admission letter from Oxford University.
—_______
| A．Good luck! | B．Congratulations! |
| C．Why so soon? | D．Don’t worry． |
In my opinion, everyone has periods in their lives _______ everything seems very hard.
| A．when | B．where | C．which | D．that |