[You say: "Hello."] = You say a word that people often say when they see someone, before they say other words. You say this word to someone because you want them to know you are here, and then they can say this same word to you to tell you that they can hear you. You want to know they can hear you before you start saying more to them.
[When I saw someone moving towards me, I said: "Hello."]
[I say to you: "Please do X."] = I say to you: I want you to do X.
[Please give me something to eat.]
12-30. thank, thanks, to thank, thanking, thanked.
[You thank someone.] = Someone did something good for you. Because of this, you want to say something like this to them: You tell them that you feel happy when you think about them because you know they did this thing that is good for you.
[The man thanked the people who gave him something to eat.]
[You feel sorry that X happened.] = You feel sad because X happened and you know X is bad for someone. If X happened because of something you did, you feel bad because you caused it.
[I am sorry that my animal hurt you.]
Lisa gives this person some books and helps him learn to read.
He says to Lisa: "__________."