1 . The growing speed of a plant is influenced by a number of factors, _____ are beyond our control.

A．most of them

B．most of which

C．most of what

D．most of that

2 . English is a language shared by several diverse cultures, each of ________ uses it somewhat differently.

A．which

B．what

C．them

D．those

3 . （2016·浙江）Scientists have advanced many theories about why human beings cry tears, none of ________has been proved.

A．whom	B．which
C．what	D．that