______ you have finished your work, you ought to have a good rest. 

_______ a small number of Australians are bitten by spiders each year, most recover without any medical treatment.

Henry must have stayed up last night, ________ he looks so tired and sleepy.

You can borrow my car ________ you promise not to drive too fast.

He had just sent an e­mail to his pal on the Internet ________ the system broke down.