engagement : 普通用词，可与本组的另外两个词换用。泛指任何商定的地点和时间见面，专指针对某一目的约会。
- a dinner engagement
- I'm afraid I have a previous/prior engagement (= another arrangement already made).
appointment : 通常指严格根据时间表上预约的时间进行的约见或约会，其目的主要是讨论公事或业务问题。
- I'd like to make an appointment with Dr Evans, please.
- She had to cancel her dental appointment.
- I've got an appointment to see Ms Edwards at two o'clock.
- I've got a two o'clock appointment with Ms Edwards.
- If he didn't have a secretary to remind him, he wouldn't keep (= remember to be present at) any of his appointments.
- That's the second appointment he's missed.
date : 主要指朋友之间的随便约见或男女之间的约会。
- He asked her out on a date.
- She has a hot date (= an exciting meeting) tonight.