Shall and will are both modal verbs in English used to express propositions about the future. According to the New Oxford Dictionary of English, In modern English the interchangeable use of shall and will is an acceptable part of standard British and US English.
When I learned English in schools in Hong Kong, which were under the English system, we were told that for future tense first person it is I shall and 2nd or 3rd person or noun you will, he will and it will respectively. It would be wrong to say otherwise. However, under American English it is all along acceptable to say I will. As a matter of fact it is the preferred way. With the American dominant influence in the English language, I will or we will is generally used, while I shall or we shall is reserved for other uses, which I will explain below. Personally, I agree with Oxford dictionary that shall and will are interchangeable, i.e. the same. I do not know how the examination system in the Mainland views the uses of shall and will. Could anyone of my friends please tell me?
"I shall" or "we shall" indicates conviction
American English reserves the use of "I shall" or "we shall" to indicate certain conviction on the part of the speaker. The quote "I shall return" was made famous by US General Douglas MacArthur. When he told the Philippines people "I shall return." during the Second World War, he was telling them that they could count on him to come back. Therefore, when your American boyfriend tells you "I shall return". Don't treat it as he is showing you the proper use of English grammar. He is showing an commitment to you and that he will definitely come back to see you.
Shall used to give a suggestion or ask a question
For example, "Shall we go to McDonald?". The person saying this is suggesting to go to McDonald. It will be awkward or weird to say "Will we go to McDonald?"
The use of should and would
These two words are commonly used as the past tense for shall and will respectively. In addition, they have the following uses:
Should is used to show an obligation and duty, examples:
- You should not smoke in front of the children.
- You should not lie about your age.
- You should clean up the room.
Would is used to make a polite request, examples:
- Would you pick up that piece of paper on the floor?
- Would you go to the dinner with me?
Shall 和 Will 都是用来表达对未来的情态动词。根据新牛津英语词典现代英语Shall 和 Will 可以互换使用 ，此已成为英式和美式英语可接受的一部分。
当我在香港英制学校学英语是，老师教导我们 ，未来时第一人称是I shall 而第二人称或第三人称或名词称顺序为 you will, he will, it will，如非如此便是错误。不过根据美国英语，I will, we will 一直以来同时可以接受 ， 其实I will, we will 是他们较为接受的方式。随着美国在英语支配性影响力，I will, we will 反为较普遍使用， 而I shall 则留作其他用途，我将在下面解释。就我个人而言，我同意牛津词典 Shall 和 Will 是可以互换的看法 ，但我不知道内地考试制度看法如何，请你们告诉我。
I shall 或 we shall 表示承诺
美国英语 I shall 或 we shall 限制使用以显示一个人的承诺。I shall return 这引用是由著名的美国将军麦卡瑟在第二次世界大战时对菲律宾人民说出已成为佳话，他是对当地人承诺他一定回来。因此当你的美国男友告诉你 I shall return, 不要把它当作他教你正确语法，他其实对你承诺他一定会回来看你。
Shall 用于提出建议或质询例如，Shall we go to McDonald？ “咱们去麦当劳吧！” ，这表示要去吃麦当劳。如说Will we go to McDonald？这有点怪异。Should 和 would 的用法这两个词通常用作过去时 ，此外它们有以下用途：
- You should not smoke in front of the children 你不应该在孩子面前吸烟。
- You should not lie about your age 你不应该就您的年龄撒谎。
- You should clean up the room. 你应该清理房间。
- Would you pick up that piece of paper on the floor? 你可不可以拾起地上那一张纸？
- Would you go to the dinner with me? 请问你和我一起吃饭可以吗？