20．According to a recent US survey，children spent up to 25 hours a week　　　　 TV.

　　　 A．to watch　　 　 B．to watching　　 　　　　　　　　　　　　　　　 C．watching 　　　 D．watched

19．Boris has brains．In fact，I doubt whether anyone in the class has 　　　　IQ.

　　　 A．a high　　 　　　　 B．a higher 　　　　　 C．the higher 　　　 D．the highest

18．Rainforests　　　 and burned at such a speed that they will disappear from the earth in the near future.

　　　 A．are cutting down　 　　　　　　　　　　　　 B．are cut down

　　　 C．are being cut down 　　　　　　　　　　 D．had been cut down

17．American women usually identify their best friend as someone　　　 they can talk frequently.

　　　 A．who 　　　　　　　　 B．about which　　 　　　　　　　　　　　　　　 C．as　　　　　　　 D．with whom