单选题 Both sugar and salt can ______in water.

单选题 This is not what we asked you to do. You can not get more pay for the _______ work.

单选题 Water and air are _______ to human beings. We can not live without them.

单选题 In the class the teacher asked the students to _______ their bad habits.

单选题 Chocolate and ice-cream have different _______.

单选题 Please _______ me for my rudeness. I really do not know the custom here.

单选题 This is an _______ that will not be easily forgotten.

单选题 When the airplane takes off, the passengers are told to _______ their seat belts.

单选题 When you study in the United States, usually you have to buy your own health _______.