－Hello, Mary! This is John. You must know why I you.
－Oh, hello, John! I've waited for this call since last month.
A. called
B. am calling
C. was calling
D. have called
网友回答
A. called
(答案→)B. am calling
C. was calling
D. have called
解析：考查动词时态的用法。两人正在电话通话，而且后面提到的电话也是这个电话，排除了其他时间的电话。所以“我给你打电话”用现在进行时。