How do you make a submit button in HTML5?

问题:

Given W3C's HTML5 spec for the submit button:

A button element must have both a start tag and an end tag.

what's an example of a submit button with a start and end tag?

1. <button type="submit">
2. <button type="submit" />
3. <button type="submit" ></button>
4. 2 & 3
5. None of the above

Is the answer the same for other "singleton" tags, like <input> or <img>?

回答1:

<button type="submit">Click me</button>

W3C and MDN has more information.