If you find yourself ______ no one will help you, please call me.
| A．which | B．when |
| C．where | D．what |
A sudden stop can be a very frightening experience，______ if you are travelling at high speed．（ ）
| A． |
eventually |
B． |
strangely |
C． |
merely |
D． |
especially |
When their children lived far away from them，these old people felt ______from the world．（ ）
| A． |
carried away |
B． |
broken down |
| C． |
cut off |
D． |
brought up |
Scientists have advanced many theories about why human beings cry tears，none of ______ has been proved．（ ）
| A． |
whom |
B． |
which |
C． |
what |
D． |
that |
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 |