He was about to leave the office for home _______someone knocked the door and asked for some help.
| A．until | B．while |
| C．as | D．when |
To return to the problem of water pollution，I'd like you to look at a study _______ in Australia in 2012．（ ）
| A． |
having conducted |
B． |
to be conducted |
| C． |
conducting |
D． |
conducted |
Silk ______ one of the primary goods traded along the Silk Road by about 100BC．（ ）
| A． |
had become |
B． |
was becoming |
| C． |
has become |
D． |
is becoming |
We can achieve a lot when we learn to let our differences unite，rather than _______ us．（ ）
| A． |
divide |
B． |
reject |
C． |
control |
D． |
abandon |
The study suggests that the cultures we grow up _______influence the basic processes by which we see world around us．（ ）
| A． |
on |
B． |
in |
C． |
at |
D． |
about |
That young man is honest，cooperative，always there when you need his help．______，he's reliable．（ ）
| A． |
Or else |
B． |
In short |
| C． |
By the way |
D． |
For one thing |