4.听下面一段材料,回答19至21题 19.Where's the man's mother now? A.In the hospital. B.At home. C.In the office. 20.Why is the man worried about his mother? A.Because his mother is badlyill. B.Because his mother is old. C.Because his mother is aloneat home. 21.What does the woman think of the man? A.He is a kind and carefulson. B.He is not careful enough. C.He is hard-working.