________ he has limited technical knowledge, the old worker has a lot of experience．

A．Since

B．Unless

C．As

D．Although

This is a very interesting book．I'll buy it, ________．

A．no matter how it may cost

B．how may it cost

C．how much may it cost

D．however much it may cost

－Mom, what did your doctor say?

－He advised me to live ________ the air is fresher．

A．in where

B．in which

C．the place where

D．where

If you travel ________ the customs are really foreign to your own, please do as the Romans do．

A．in which

B．what

C．when

D．where

In time of serious accidents, ________ we know some basic things about first aid, we can save lives．

A．whether

B．until

C．if

D．unless

________ you've tried it, you can't imagine how pleasant it is．

A．Unless

B．Because

C．Although

D．When

________ homework did we have to do that we had no time to take a rest．

A．So much

B．Too much

C．Too little

D．So little

His plan was such a good one ________ we all agreed to accept it．

A．as

B．that

C．so

D．and

I'd like to arrive 20 minutes early ________ I can have time for a cup of tea．

A．as soon as

B．as a result

C．in case

D．so that

A man cannot smile like a child, ________ a child smiles with his eves．while a man smiles with his lips alone．

A．so

B．but

C．and

D．for