A: What's that?<br/>B: (It's/That's) a library.<br/><br/>A: Who's that?<br/>B: (It's/That's/He's) Tom.<br/><br/>A: I saw a bad accident. Some people were badly injured. (It's/That's) scary.<br/>B: Oh, (It's/That's) frightening.<br/><br/>Which is better, "It" or "That"?<br/><br/>Thank you.