问题 计算题

今年海口市春节前天气潮湿寒冷,小明的妈妈给爷爷奶奶买了一床电热毯,该电热毯有高温、低温两挡,通过单刀双掷开关S进行调节,R0为电热丝.当开关S接高温挡时,电路的功率为88W,当开关S接低温挡时,电路的总功率为22W.

(1)电热毯在高温挡时,开关S应与哪个触点连接?请简要说明理由;

(2)电热丝R0的阻值多大?

(3)当电热毯在低温档工作时电路中的电流多大?工作30min,电热丝R0消耗的电能是多少?

答案

解:

(1)S应与2接触,由,当电路中R最小时,P最大,S接在2触点时,R被短接,电路中只有R0工作(合理即可)

(2)

(3)

阅读理解

Are you looking for some new and exciting places to take your kids (孩子) to? Try some of these places

★Visit art museums. They offer a variety of activities to excite your kids' interest. Many offer workshops for making hand-made pieces, traveling exhibits, book signings by children's favorite writer, and even musical performances and other arts.

★Head to a natural history museum. This is where kids can discover the past from dinosaur(恐龙) models to rock collections and pictures of stars in the sky. Also, ask what kind of workshops and educational programs are prepared for kids and any special events that are coming up.

★Go to a Youtheater. Look for one in your area offering plays for child and family visitors. Pre-show play shops are conducted by area artists and educators where kids can discover the secret about performing arts. Puppet(木偶)making and stage make-up are just a couple of the special offerings you might find.

★Try hands-on﹙动手﹚ science. Visit one of the many hands-on science museums around the country. These science play-lands are great fun for kids and grown-ups alike. They'll keep your child mentally and physically active the whole day through while pushing buttons, experimenting, and building. When everyone is tired, enjoy a fun family science show, commonly found in these museums.

小题1: If a child is interested in the universe, he probably will visit        

A.a Youtheater

B.an art museum

C.a natural history museum

D.a hands-on science museum小题2:What can kids do at a Youtheater?

A.Look at rock collections.

B.See dinosaur models.

C.Watch puppet(木偶) making.

D.Give performances.小题3: Where does this text probably come from?

A.A science textbook.

B.A tourist map.

C.A museum guide.

D.A news report.

单项选择题