Mr Smith's lived in Guangzhou for many years, _________.

[　　]

He had nothing for breakfast this morning, _________?

[　　]

Doctors began to learn more about ________ made people sick.

[　　]

Now the population ________ ________ forty years.

[　　]

Nick had nothing for breakfast, ________?

[　　]

We _______ friends since the first day of primary school.

[　　]

单选

please ________ your new dress to me.

[　　]

单选

I often help him ________ the classroom.

[　　]

单选

I like to hear the bird ________ in the morning.

[　　]

单选

Do you know the answer ________ the question?

[　　]