Modals - "could" or "should"?

source: JamesESL English Lessons (engVid)    2014年10月1日
http://www.engvid.com/ Expectation is what we think could or should happen. But COULD and SHOULD are not the same! This important grammar lesson will teach you how to use these modals correctly, like a native English speaker. You SHOULD take the quiz to test yourself!
http://www.engvid.com/learn-english-g...

# click this line for more videos on  modals: expressing obligation and necessity