Here are the steps on how to activate Google's AI-powered grammar checker:
1. Go to Google Search.
2. Type in a sentence or passage that you want to check for grammar errors.
3. Add the phrases "grammar check," "check grammar," or "grammar checker" to the end of your query.
4. Click on the "Search" button.
5. Google will highlight any areas of your writing that it believes could be improved, and it will also provide suggestions for how to fix the errors.