A、It was invented after observing volunteers. B、It was coined by college professors in the lab. C、It was stimulated by the screa

W: Good morning and welcome to the show. Today’s topic should be interesting to anyone who has ever had to deal with a screaming and frustrated baby! I’m watching a baby sign language class at Parent’s Corner in Lower Manhattan, and I’m talking to Joan Lee, who’s the director of the program. Joan, good morning!
M: Good morning!
W: So these babies are learning sign language?
M: Well, we’re not exactly teaching the babies. We’re teaching the parents some basic signs that they can use with their babies.
W: What kind of signs are you teaching them?
M: (19)Well we start with signs for the most important things in babies’ lives. . . signs for things like "more, " "milk, " "up". . . that kind of thing.
W: The things babies need to say!
M: Yes, exactly.
W: Where did the signs come from? Did you make them up?
M: Oh no. (20)Most of the signs are taken from ASL. . . American Sign Language.
W: How old are the babies?
M: The youngest is four months, and the oldest is about eighteen months.
W: That’s incredible! Now what are the advantages of doing this?
M: (21)Well, mainly it’s much easier for the parents, and actually for the babies too, if they can communicate. You can figure out what they want. It’s very frustrating when your child is screaming his head off and you don’t know what he wants.
W: I see. Where did this idea come from?
M: (22)From watching deaf children. Some years ago, researchers noticed that deaf children learn to use hand signals earlier, much earlier, than hearing children learn to speak.
19. Q: What does the man teach parents in the language class at first?
20. Q: What do we know about the signs?
21. Q: What are the advantages of using sign language?
22. Q: How did the idea of teaching babies’ sign language come into being?