问题 选择题

自然界中有许多奥妙的声,声音是人们交流信息的重要渠道,是日常生活中经常接触到的物理现象。下列有关声现象的说法错误的是(  )

A.用牙齿听声利用的是骨传导

B.用超声能击碎人体内的结石,说明声波具有能量

C.利用声波和电磁波都可以传递信息

D.市区内某些路段“禁鸣喇叭”,这是在声音传播的过程中减弱噪声

答案

答案:D

A、牙齿是固体,可以传播声音,即骨传导现象.正确.

B、人们利用超声波的能量,击碎体内的结石.正确.

C、声波和电磁波都可以传递信息.正确.

D、禁鸣喇叭是在噪声的产生处进行减弱的.错误.

故选D.

单项选择题
阅读理解

阅读理解。

     Do's and Don'ts in Whale (鲸) Watching

     The Department of Fisheries and Oceans has developed guidelines for whale watching in Johnstone

Strait, where killer whales are found on a daily basis each summer. It is strongly recommended that

vessel (船只) operators follow these guidelines for all kinds of whales.

     Approach whales from the side, not from the front or the back.

     Approach no closer than 100 metres, then stop the boat but keep the engine on.

     Keep noise levels down-no horns, whistles or racing of engines.

     Start your boat only after the whales are more than 100 metres from your vessel.

     Leave the area slowly, gradually moving faster when you are more than 300 metres from the whales.

     Approach and leave slowly, avoiding sudden changes in speed or direction.

     Avoid disturbing groups of resting whales.

     Keep at low speeds and remain in the same direction if traveling side by side with whales.

     When whales are traveling close to shore, avoid crowding them near the shore or coming between

the whales and the shore.

     Limit the time spent with any group of whales to less than 30 minutes at a time when within 100 to

200 metres of whales.

     If there is more than one vessel at the same observation spot, be sure to avoid any boat position that

would result in surrounding the whales.

     Work together by communicating with other vessels, and make sure that all operators are aware of

the whale watching guidelines.

1. For whom is this text written?

A. Tour guides.

B. Whale watchers.

C. Vessel operators.

D. Government officials.

2. When leaving the observation areas, the vessel should _________.

A. move close to the beach

B. increase speed gradually

C. keep its engine running slowly

D. remain at the back of the whales

3.When going side by side with whales, the vessel should _________.

A. travel closer and closer to the shore

B. surround the whales with other boats

C. keep moving in the same direction

D. take a good viewing position

4. What is the shortest safe distance from the whales?

A. 400 metres.

B. 300 metres.

C. 200 metres.  

D. 100 metres.