See the flags on top of the buildings? That was ________ we did this morning．

A．when

B．which

C．where

D．what

－I'm going to the post office．

－________ you're there, can you get me some stamps?

A．As

B．While

C．Because

D．If

－Your performance in the driving test didn't reach the required standard

－________, you failed．

A．in the end

B．after all

C．in other words

D．at the same time

The bridge, which ________ 1688, needs repairing．

A．is dated from

B．was dated from

C．dates from

D．dated from

With a lot of difficult problems ________, the newly-elected president is having a hard time．

A．settled

B．settling

C．to settle

D．being settled

Unless ________ to speak, you should remain silent at the conference．

A．invited

B．inviting

C．being invited

D．having invited

When first ________ to the market, these products enjoyed great success．

A．introducing

B．introduced

C．introduce

D．being introduced

There were dirty marks ________ she had wiped her hands．

A．where

B．which

C．when

D．that

Roses need special care ________ they can live through winter．

A．because

B．so that

C．even if

D．as

You'd better take something interesting to read when you go to see the doctor, who is usually busy ________ you have to wait．

A．even if

B．in case

C．as if

D．in order that