Being able to act emotions as if they are really experiencing those kind of emotions, if you have to be incredibly sad, you have to pay a lot of attention to your facial expressions, someone who is trained in reading facial expression to find out how they feel will easily be able to see if sadness is fake or real. A good actor would try to call up a moment in his life in which he felt similar emotions and replay that moment in their head, they'll then experience those emotions again, as in, they are ACTUALLY experiencing the emotions they have to act, not just acting them. That, is true acting.
My nation is not like my nation page at all, it contradicts itself, we don't EVER eat kangaroos, that's just very sad. Also vegetarianism is compulsory yet it still says it's the nation's favourite main course and all and stuff.