1. Click the text input area, the keyboard appears, and click "Symbol".
2. We can see that there are various types of symbols to choose from at the bottom of the keyboard. We choose "English".
3. At this point, we can see the underline symbol, as shown in the figure. Click the underline symbol once to input the underline, and click the symbol several times to input multiple underscores.
4. Let's try to enter underline and letters.
5. The input method of iPhone is as follows: Adjust the input method to Chinese input status.
6. Press "123" in the lower left corner.
7. Then click "#+=" on the keyboard.
8. The underline will appear, and click Select.