单选题 ____ the teacher ____ his student object to the change.

单选题 The experiment failed. It was, ____, worth making.

单选题 The pilot ____ two of the passengers has miraculously escaped death.

单选题 He didn’t work hard; ____, he failed his exam.

单选题 Bicycling is a good exercise; ____, it doesn’t pollute the air.

单选题 The new car is smaller and ____ cheaper.

单选题 The doctors and nurses did ____ they could ____ the dying man.

单选题 ____ coal, the most important natural fuel are gas and oil.

单选题 ____ fans ____ an air - conditioner is necessary for this laboratory.