Dear Peter,
Thanks very much on inviting me to your birthday     86.  ________
party on Sunday. I'd like very much come but         87.  ________
I had an examination on Monday morning. It is        88.  ________
a very important exam but I can't afford to          89.  ________
fail it. I'll spend all the whole weekend reading     90.  ________
and prepare for it. So I'm really sorry that         91.  ________
I won't be able to come in this time. Hope you        92.  ________ 
can understand. I'll take this chance to wish        93.  ________
you wonderful time on your birthday. Happy           94.  ________
birthday, Peter, and many happy return of the day!    95.  ________
Yours,
Li Ming