题目

下列化合物的分子式可能代表一种以上物质的是：    （    ）    A．C3H8    B．C4H10 C．CH3Cl   D．CH2Br2  答案：B解析:略 听下面一段材料，回答第1至2题。 1. What’s the relationship between the two speakers? 　　 [     ]A. Schoolmates.　　　B. Colleagues.　　　C. Teacher and student. 2. What’s Mark’s attitude towards the test? 　　 [     ]A. He worries about it.　　　B. He is calm.　　　C. He has to get an A.