Callan Stage 8 New Edition Lesson 126 ''GRAMMAR QUESTIONS'' -->78) When do we use "could" as the past of "can"? Give me an example.

レッスンで出てきた文法・単語	GRAMMAR QUESTIONS: SENTENCE STRUCTURES: •When we talk about general abilities in the past.  •We use "could" as the past of "can" to speak about general abilities.  •We don't use "could" as the past of "can" if we talk about a particular occasion when somebody managed to do something.  •We use "was able", managed" or "succeeded" instead  •We express a future idea with "should" or "ought to" by using a word or phrase that expresses future time.  •One common way of making a request is to say "Can you ...?" or "Could you ...?" For  •"Could" is more polite than "can".  •Another common way of making a request is to say Do you mind ..?" or "Would you mind ..?"  •would say "Would you mind ...?" if I wanted to be especially polite.  •If somebody says that they needn't have done something, it means that they did it, but it was, in fact, not necessary
レッスンで利用した教材	CALLAN NEW EDITION STAGE 8
レッスンで利用した教材のページ数	None