释义：
I'm calling to... 我打电话是为了……
用在说明给对方打电话的目的。 I'm calling to because…或 I'm calling to+动词都可以。另外，过去式为 I called to+动词。
例句：
I'm calling you because I saw that you called me.
我看到你给我来了电话，才打给你的。
I'm calling about tomorrow's meeting.
我打电话是为了明天的会议。
I called to apologize.
我打电话是想道歉的。
对话：
A: I'm calling to talk to Mr. Kang in the marketing department.
我要打给营销部的姜先生。
B: I'm sorry, but he isn't in the office right now.
不好意思，他现在不在办公室。
