Hello, Unfortunately, I don't speak Chinese, but I hope you'll be able to translate my answer. Firefox Focus is '''free''', just as Firefox desktop, Firefox for Android or Firefox for iOS. As for now, Firefox Focus is not available for desktop, but you can vote for [https://connect.mozilla.org/t5/ideas/the-possibility-of-firefox-focus-for-desktop/idi-p/21802 this idea] on Mozilla Connect. Also, if you're looking for more privacy, check out [[Private Browsing - Use Firefox without saving history | Firefox's Private Browsing]].