题目

下列古代文明或工艺一定包含化学变化的是( ) A．在甲骨上刻字  B．指南针指引航海 C．用泥土烧制陶瓷  D．用石块修筑长城 答案：CA survey of the opinions of experts           that three hours of outdoor exercise a week is good for one’s health.A. show                      B. shows                C. is shown