A.+→
B.→+
C.+→
D.→+
答案:D
下列那些物质是无机物?()
A.硫化氢
B.苯
C.二氧化碳
D.乙醇
Many of them turned a deaf ear to his advice, even though they knew it to be _____.[ ]
A. valuable
B. reliable
C. flexible
D. acceptable