你的好友Tom邀请你本周末参加他的周末派对。假定你是陈蕾，请你回一封邮件，婉言拒绝他的邀请， 根据你的日程表说明原因，其中周六理由已给出，周日可作适当发挥。字数80字左右。

weekend schedule
Saturday	Sunday
Morning: have an English class prepare for the math test	Morning:……
Afternoon: go to the dentist	Afternoon:……
From:	[e-mail]
Subject:	Sorry,but I'm not available.
Hi_____,
Thanks so much for your invitation. I'd love to come to the party, but…
yours,
________