练习1. The _ question is much more difficult than this one. A. sixth B. six C. sixteen D. sixtyA2. We can see _ stars at night if there are no clouds in the sky. A. thousand of B. thousands of C. a thousandB3. -How much does it cost to build the school library?-Four _ Yuan. A. million B. millions C. million of D. millions ofA4. In our city, _ middle school students want to work as a teacher in the future. A. thousand B. thousand of C. thousands of D. two thousand ofC5. During World War , a Jewish
