These are some of the summary from my english lecture today. Albeit these are not a rocket science, I think these will be a good refreshment about our english language.
What is the difference between 'could' and 'can'? For example, "could you please show me their difference?" and "can you show me their difference?". 'Could' has a meaning of possibility and 'can', on the other hand, has a meaning of ability. As a result, the former sentence has a meaning of "Is it possible for you to show me their difference" which is more polite compared to the latter sentence which has a meaning of "You have the ability and show it to me".
Next, what is the difference between 'would' and 'could'? For example, "I would help you" and "I could help you". Both 'would' and 'could' have a meaning of possibility. The former means it has a possibility in the future and not right now. But the latter means it has a possibility right now. In other words, The former sentence means "I will help you if I can" and the latter sentence means "I can help you right now if I want to".
Written by: Xaivier Chia
