COPD病人的共同特点是（）。
A.以吸气困难为主的呼吸困难
B.以呼气困难为主的呼吸困难
C.吸气、呼气均困难
D.气道阻塞
E.以上都正确
参考答案：D
找出错误并改正。
1. Today is sunday.
2. It my Chinese teacher.
3. Mr Green' birthday.
4. He is 35. This's a new watch.
5. It not is blue. It's yellow.
6. It's very beautiful. It's for she.
能够经过催化加氢得到2甲基戊烷的烯烃有 ( )
A．2种
B．3种
C．4种
D．5种
