介绍： 1.

A. Electrical interference.

B. Cloud.

C. Smog.

D. Greenhouse gases.



2.

A. Trees and wind.

B. Rivers and hills.

C. Sun and stars.

D. Wings and tail.



1. According to the report, what has been disrupting the sense of direction of some birds?

A. Electrical interference.

B. Cloud.

C. Smog.

D...

介绍： 1.

A. Electrical interference.

B. Cloud.

C. Smog.

D. Greenhouse gases.



2.

A. Trees and wind.

B. Rivers and hills.

C. Sun and stars.

D. Wings and tail.



1. According to the report, what has been disrupting the sense of direction of some birds?

A. Electrical interference.

B. Cloud.

C. Smog.

D. Greenhouse gases.



2. According to the report, what do birds use as a back-up system?

A. Trees and wind.

B. Rivers and hills.

C. Sun and stars.

D. Wings and tail.

答案：AC

Some birds perform remarkable（卓绝的） feats（技艺表演; 卓绝的手艺，技术，本领;武艺;） of navigation（航行）, migrating（迁移，移动） halfway around the world. And it’s thought that a built-in compass（指南针）, which senses（感觉到） the Earth's magnetic field（磁场）, helps them to find their way. But this latest study suggests that low frequency waves produced by devices plugged into the mains electricity（主流电源）, could be interfering（干扰） with this 'inner（北部的） satnav（[卫星]导航仪）'. Scientists found that migratory birds（候鸟）exposed to this electromagnetic noise（电磁噪声）lost all sense of direction. But when the field was blocked out（屏蔽）, they found their bearings（方位） again. Researchers believe electrical interference could be a particular problem when birds flyover urban areas. They think the birds are forced to switch to back-up（备用的） navigational systems, staying on course using the sun and stars instead.