[{"Bold_text": "auxiliary verb", "List Items": ["a simple past tense of can1 .", "(used to express possibility):I wonder who that could be at the door. That couldn't be true.", "(used to express conditional possibility or ability):You could do it if you tried.", "(used in making polite requests):Could you open the door for me, please?", "(used in asking for permission):Could I borrow your pen?", "(used in offering suggestions or advice):You could write and ask for more information. You could at least have called me."]}]