–What’s the noise ? It sounds as if it comes from upstairs.  

--______. It must be the window-cleaner working , next door.         

A．I’m not sure

B．I hope not

C．I’d rather not

D．I don’t think so

某地区有部分儿童出现智力低下，生长发育迟缓，应重点考虑

A．汞中毒

B．铅中毒

C．地方性砷中毒

D．地方性克汀病

E．地方性氟中毒