All ________ is needed is a supply of oil．

A．the thing

B．that

C．what

D．which

The buses, ________ were already full, were surrounded by an angry crowd．

A．most of them

B．most of which

C．which most

D．that most

He must be from Africa, ________ can be seen from his skin．

A．that

B．as

C．it

D．what

The reason ________ he didn’t come was ________ he was injured．

A．that, because

B．why, that

C．why, because

D．that, that

Can you solve such problems ________ raised by the audience?

A．what were

B．as were

C．that were

D．which were

I have bought the same dress ________ she is wearing．

A．as

B．that

C．which

D．than

Lessons ________ easily were soon forgotten．

A．to learn

B．learn

C．learned

D．learning

The ground is ________ with ________ leaves．

A．covering, falling

B．covered, falling

C．covered, fallen

D．covering, fallen

The student corrected his paper carefully, ________ the professors suggestions．

A．follow

B．following

C．followed

D．being followed

________ the office, the foreign visitors were shown round the teaching building．

A．Having shown

B．Showing

C．Has shown

D．Having been shown