I tried to use flash player on firefox but It seems that there should be a bug in flash player, the picture is magnified and I can’t see the whole picture. I used flash player to do homework but I cannot read the question and check the answer.
Flash Player is extensively tested on all supported platforms, including Firefox. This is the first report of this issue I've seen. While it's possible to be a Flash Player issue, isolated issues usually tend to be system specific.
Right-click on the content to display the Flash Player context menu and verify that `Show All' is selected and the content isn't zoomed in.
Please provide a direct link to content that isn't working, assuming it's publicly available.
I also recommend reporting this issue to the content provider.
Yeah, it could be a few things, but zooming out and/or trying different browsers is probably your best option. It's unlikely that it's Flash per-se, but probably a combination of how scaling is working at the intersection of your browser, operating system, display and how this particular site is built.
For a more specific recommendation, some details would be helpful:
Any chance you're on Firefox 81 on Mac? It looks like they broke something in their latest update. It's working as expected in Firefox 82 nightly.