单项选择题
A. the ground where birds like to live B. the place where birds usually live C. the tree-tops, the air and the water D. rules that hold true for most birds
A. tree rings grow close together B. tree rings grow far apart C. trees in New Mexico will grow big and tall D. people can cut down most of the trees in New Mexico
A. 1,000,000 B. 500,000 C. 3,000 D. 30,000