–Don’t you tell me that they have gone to Australia?
-Sure.But I don't know _________.
A.when they have come back
B.when have they come back
C.when did they come back
In our school library there a number of books and the number of them growing
larger and larger.
| A．is; are | B．has; is |
| C．are; is | D．have; are |
The workers were made from morning to night in the past.
| A．worked | B．to work | C．work | D．working |
—Are all the students from in your class?
—No, there are only three in our class. The others are from other countries.
| A．Germany; Germen | B．Germany; Germans |
| C．German; Germans | D．German; Germany |
Jack is nine years old. Today is his birthday.
| A．nine | B．ninth | C．nineth | D．ninety |
—How happy the grandparents are!
—Yes, they for fifty years.
| A．have been married | B． have married |
| C．How got married | D． married |