有关一氧化碳和二氧化碳的比较，下列说法错误的是 [ ]
A．两者都有毒
B．都是纯净物
C．都可由碳与氧气反应得到
D．组成元素都相同
答案：A
所有返工/返修后的产品必须按规定的程序/文件再作检验，但不一定要全部符合原来规定的要求。（）
— I _____ to get to the South Mall. Could you tell me which bus I should take?
— Just catch the No. 10 bus from here. It's the 4th stop. [ ]
A. am trying
B. would try
C. tried
D. have tried
