When you select "import" > "Select a Course' > where Only 'Include Activities' is checked > and deselect ALL the many activities you don't want (because there is NO "select/deselect all' toggle) and click "import' and go into the Question Bank in your target course, you will notice to your dismay, that ALL the Categories & Questions from the source course have been imported also. This results in a lot of work to delete out all the unwanted questions and categories from the target.