根据句意,选用适当的词填空。 1. —Is this your pencil? —No,it isn't. ______ (That,That's) my pencil. 2. —What's this? —______(It's, Its) a red pen. 3. I can see______ (a, an) English girl. 4. —______(What's, What)color is the clock? —It's white. 5. —Excuse ______ (I, me),Sally. Is this your book? —No, it isn't.