哌替啶是（）的化学名称。
A、K粉
B、摇头丸
C、杜冷丁
D、麻古
参考答案：C
Choose and write.选择合适的单词填空。
1. Many animals are____ (in/on) the farm.
2. This is a____ (cow/cows).
3. Old MacDonald is a____ (farm/farmer).
