答案：46.hearing　47.can't　48.invitation　49.to study　50.to have

Ⅵ.

　　答案：51.E　52.A　53.B　54.C　55.F

Ⅶ.

　　答案：Dear Tom，

　　Thank you very much for inviting me to your birthday party.I'd love to go but I can't.My parents are out on business.They are coming back next month.And now I have to look after my grandmother because she is ill in bed.And I also need to study for my coming English exam.I'm very sorry but I can't go to your party.Thank you for asking me.I hope you can have a good time.

　　Yours，

　　Li Ping