Parents should take seriously their children's requests for sunglasses ________ eye protection is necessary in sunny weather．

A．because

B．though

C．since

D．if

It is almost five years ________ we saw each other last time．

A．before

B．since

C．after

D．when

“You can't have this football back ________ you promise not to kick it at my cat again,”the old man said firmly．

A．because

B．since

C．when

D．until

It was not until she got home ________ Jennifer realized she had lost her keys．

A．when

B．that

C．where

D．before

－Why didn't you tell him about the meeting?

－He rushed out of the room ________ I could say a word．

A．before

B．until

C．when

D．after

－How long do you think it will be ________ China sends a manned spaceship to the moon?

－Perhaps two or three years．

A．when

B．until

C．that

D．before

The cost of living in Glasgow is among the lowest in Britain, ________ the quality of life is probably one of the highest．

A．since

B．when

C．as

D．while

How can you expect to learn anything ________ you never listen?

A．in case

B．even if

C．unless

D．when

I had just stepped out of the bathroom and was busily drying myself with a towel ________ I heard the steps．

A．while

B．when

C．since

D．after

Such ________ the case, I couldn't help but ________ him．

A．being; support

B．is; to support

C．has been; supporting

D．be; supported