Analyze sentence "I'm tired." From the perspective of syntax, it consists of ___________. From the perspective of semantics, it can be used to describe ___________, and it is necessary to decide whether this description is __________. From the perspective of pragmatics, it can be regarded as a reply to : (1) "Can you get me some food?", in this case, it means _________________. (2) "Why don't you get yourself something to eat?", in this case, it means _______________. (3) "Are you alright?", in this case, it means_______________.