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3-52.

A. Hello, James. Im calling to invite you to a dinner party to my parents. My young brother has at last got his driving license and my parents decided to celebrate the occasion.
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B. Thank you for your invitation and congratulate your brother for me. Unfortunately, I dont think I can possibly come as I have a previous engagement I cant put off.
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A. Thats bad. The boy will be disappointed.
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to mark/to celebrate / -
occasion ()
a driving license
(to have) a previous engagement
I dont think I can ,
Thats bad. .
unfortunately
I cannot possibly come.
to put smth off / -
Congratulate him for me. / .