A：盐酸
B：硫酸
C：烧碱
D：纯碱
用所给出的词语造句。
①祝贺：
②勇敢：
——I often have hamburgers for lunch.
——You'd better not. It's bad for you _________ too much junk food.
一个圆环，外圆半径是6厘米，内圆半径是4厘米，圆环面积是____平方厘米。
