Подбор синонимов:
just1, bobbed1, were1, sure1, left1, had1, Jim1, bobbing1, sink1, try1, apple1, water1, keep1, bob1- bob up
а появляться на поверхности, всплывать If you try to sink an apple in water, it will keep bobbing up. б появляться неожиданно Jim bobbed up just when we were sure that he had left.