题干
________ tourists like to climb the Great Wall, and ________ them is increasing now.
A：A great number of; a number of
B：The number of; the number of
C：The number of; a great number of
D：A great number of; the number of
答案(点此获取答案解析）
D
的一条切线l与直线
垂直，则l的
方程为（ ）
