7×1×3＝21；____；____；____

长为1的一根绳，恰好可围成两个全等三角形，则其中一个三角形的最长边x的取值范围为（　　）

阅读理解

      Mr. Smith made many tests with different animals and the monkey was the cleverest of all the animals.

      One day Mr. Smith put a monkey in a room. He also put some small boxes in it. In one of the boxes there was some food. "How long will it take the monkey to find the food?" Mr. Smith said to himself. "Let me wait and see." He left the room and waited outside. Three minutes later, he put his eye to the keyhole. What did he see? He saw the eye of the monkey. The monkey was on the other side of the door and looked at Mr. Smith through the keyhole.

下列物质在氧气中燃烧的现象，正确的是(  )

如图是在抢救伤员时，医护人员所用的一些急救措施．以下叙述不正确的是（　　）