题目

.( 湖南卷31). I walked slowly through the market, Where people_________ all kinds of fruits and vegetables. I studied the prices carefully and bought what I needed. A. Sell           B. were selling       C. had sold         D. have sold 答案：B甲、乙、丙是三种常见单质，X、Y、Z是常见化合物，他们之间有如下转化关系：已知甲是短周期金属单质，乙、丙是短周期非金属单质，X、Y、Z中只有一种是离子晶体。下列说法不正确的是A．X是具有极性键的非极性分子B．Z是水煤气的主要成分之一C．甲和X的反应是吸热反应D．丙是生产硅的重要原料