To select elements that match multiple selectors at the same time using querySelectorAll(), you can use a comma-separated list of selectors within the parentheses. This will return a NodeList containing all elements that match any of the specified selectors.
For example, say you want to select all elements with the class "red" and all elements with the class "blue":
```javascript
const redAndBlueElements = document.querySelectorAll('.red, .blue');
```
In this example, `redAndBlueElements` will contain all elements that have either the "red" or "blue" class (or both).