Seven _________ workers work in that factory.

A. thousands of          B. thousands          C. thousand

My sister says that she would like to work in that flower shop which ________ two years ago.

[　　]

He began to work in that hospital in 2003 ________ a doctor.

A. as

B. on

C. at

D. in

用所给单词的适当形式填空

There are ________ (fifth) ________ (work) in that factory.