单项选择题A.To correct a common misunderstanding about grasshoppers.B.To help explain how well grasshoppers can jump.C.To compare the size of grasshopper with that of other insects.D.To show how quickly grasshoppers respond to danger.
单项选择题A.The professor is old.B.The professor is lazy.C.The professor is sick.D.The professor is only tired.