“竹叶青”指的是一种什么动物？
参考答案：
“竹叶青”指的是一种蛇。
The old man, _____ abroad for twenty years, is on the way back to his motherland. [ ]
A. to work
B. working
C. to have worked
D. having worked
工人阶级最有远见性、最大公无私和最具有革命的彻底性。（）
