（）是指使用日久自然磨损或其他种种原因造成票币损伤，而不能在市场上继续流通的货币。
A.损伤票币
B.无用票币
C.无效票币
D.残缺票币
参考答案：A
句型转换。
1. I am too tired. I can't do it well. (改为同义句)
I am _____ tired _____ do it well. I am _____ tired _____ I can't do it well.
2. The boy is eight years old. He can go to school. (改为同义句)
The boy is _____ _____ _____ go to school.
3. The couple has a lot of money. They can buy a car. (改为同义句)
The couple has _____ _____ _____ buy a car.
4. Let's go to the zoo, _____ _____? (反意疑问句)
5. Let us go to the zoo, _____ _____? (反意疑问句)
管钳要经常保持清洁，防止（）。
A、不用
B、掉漆
C、借用
D、生锈
