1 . _______ is known to us all that the old scientist, for _______ life was hard in the past, still works hard in his eighties.

A．As; whose	B．It; whose
C．As; whom	D．It; whom

2 . Many young people, most _________ were well-educated, headed for remote regions to chase their dreams.

A．of which	B．of them
C．of whom	D．of those

3 . The settlement is home to nearly l, 000 people, many of ________ left their village homes for a better life in the city.

A．whom

B．which

C．them

D．those

4 . I have two brothers, _______ are doctors.

A．both of them

B．both of whom

C．neither of whom

D．each of them