Excuse me, this bag is too heavy. ________—Of course.

I’m tired. Let’s stop ________ and have a rest.—OK.

He is ill. I don’t know _______ he will come to school.

I could _______ by the way she walked that her knee was still bothering her.

________Switzerland (瑞士) is very small , _______it is the land of watch and it is very rich.