单项选择题
A.follow B.go C.operate D.work
A. glaciers are destructive B. all glaciers in the world move southward C. the Mississippi-Missouri-Ohio system is larger than it was before the Ice Age D. the Great Lakes are now smaller than they were before the Ice Age
A. It tells you what to produce. B. It tells you how to grow tomatoes. C. It provides you with everything you need. D. It helps you save money.