题目

Elephants would ______ if men were allowed to shoot as many as they wished. A. die down    B. die out              C. die away    D. die off 答案：B已知圆．设条件，条件圆上至多有个点到直线的距离为，则是的A.充分不必要条件 B. 必要不充分条件 C. 充要条件 D. 既不充分也不必要条件