從前, I 及 we 要配 shall ,其他如 he, she, they 等配 will 。
不過,那是舊式英文,現在 will 似乎完全取代 shall ,所以 I will 及 I shall 意思完全一樣。
現在只有兩種情況下, shall 不可以被 will 取代。
第一,當你徵求人家意見,發問時要用 shall ,如:
Shall I make tea for you?
Shall we go for a picnic tomorrow?
第二,用於訓示、規定、命令、承諾等要用 shall ,常見於法律文件如:
You shall not bring a PSP to school.
The president shall not declare war without the consent of the Diet.
You shall be rewarded.
你可參考《Common Errors in English Usage》及古德明的《征服英語》
http://www.wsu.edu/~brians/errors/shall.html
http://education.atnext.com/index.cfm?fuseaction=Article.View&articleID=5310721&issueID=20051107&pageNumber=2
http://education.atnext.com/index.cfm?fuseaction=Article.View&articleID=6064495&issueID=20060626