I introduced Netlify Large Media.
Then I Cann’t use gulp-responsive.
Cann’t I use gulp-responsive and Netlify Large Media on Netlify?
I can use gulp.js on local.
The files you add using large media are NOT AVAILABLE during build, so indeed, your build cannot manipulate them. They are just pointers that are resolved at deploy time. This is mentioned in the documentation here: Large Media overview | Netlify Docs