--- Sorry, it's already 6 o’clock. I have to be off for an appointment.
---OK. .
A. It couldn’t be better
B. You really have me there
C. Let’s call it a day
D. Take your time
网友回答
A. It couldn’t be better
B. You really have me there
(答案→)C. Let’s call it a day
D. Take your time
解析：考查交际用语：A. It couldn’t be better再好不过了。B. You really have me there你把我难住了。
C. Let’s call it a day今天就到此为此吧D. Take your time慢慢来，句意：--对不起，已经6点了，我要出去有个约会。--好的，今天就到此为此吧。选C。