30. British scientists said teenagers are programmed to take risks because they enjoy the thrill of dangerous situations________ others.
. It ________ I arrived at the station ________ I found the train was delayed.
. No teachers are permitted ________ in the classroom or in the office.
. ---I’ll be away for about two days. Would you mind taking care of my little dog? ---________.
. --- Could you fetch me my glasses from the kitchen? ---__________ .
. You can’t complain of being lonely__________you don’t make an effort to meet people and make friends with them.