Maths ________ not easy to learn.

You look well. The air and the sea food in Sanya must _______ you, I suppose.

The young couple are trying to save as much as possible ________ they can afford a flat by the end of next year

The old man lives _______ , but he never feels ________.

Do you know Chang’e Ⅲ Explorer is walking on the moon — Great! It sounds .