----is your sister?-She is thirteen years old. A. How manyB. How oldC. How muchD. How l

问题补充：

----is your sister? ---She is thirteen years old.

A. How many

B. How old

C. How much

D. How long

答案：

A. How many

(答案→)B. How old

C. How much

D. How long

解析：句意：你姐姐多大了？她13岁。询问某人的年龄用How old be sb？句型，how many表示“数量的多少”，how much修饰不可数名词，how long描述长度；故选B。