First time using italki

Hi guys, I find this website is really good(great). Most of the time we  I don't know what's<em>(what is)</em> the problem in our while talking and writing in English. If some native speakers could<em>(can)</em> correct these mistakes, I could better remember these mistakes and not to do repeat them again. It's This is a really cool way to improve my written English.

...can could...

if you can do this then I could do that. 

If you come to my house, I could make you dinner. (Can/could apply to different word meanings ...can come...could make)

very difficult to use these words perfectly but the good news is that if you use these words and you make a mistake then people can still understand you.