UN Secretary-General Ban Ki-moon left for Pakistan this morning， his assistant _________ him there this Friday.
| A．joins | B．joined |
| C．joining | D．to join |
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 |
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 |