H2S是主要作用于内分泌系统和呼吸系统。
参考答案：错
解析：H2S是主要作用于中枢神经系统和呼吸系统。
Over 50 people were killed because of a crash of city railway in Argentina____ the morning of February 22nd. [ ]
A. in
B. on
C. at
D. of
商品经济内在矛盾的产物是（）。
A.交换价值
B.商品交换
C.货币
D.信用
