题目内容：

Sound travels very well through water-much better, in fact, than it does through air. So it shouldn’t be surprising that many ocean animals make noise. They use sound to communicate and hunt. As biologist Brandon Southall says, “Their whole world is related to sound.”

Dolphins whistle, organizing hunts. Lovesick whales sing so loudly they can be heard hundreds of miles away. But these days they aren’t the only ones sounding off. They have more and more competition from human machines.

Every day, thousands of huge container ships sail across the world’s oceans. On top of the engine noise, the ships’ propeller (螺旋桨) make a loud noise all the time. All that can make it hard for ocean animals trying to listen out for friends, or dinner. Animals swimming nearby a ship can be deafened or even killed.

Underwater construction can also be dangerously loud. When construction machines called pile drivers were used during repairs to the San Francisco-Oakland Bay Bridge, dead fish appeared.

Geologist (地质学家) pound on the seafloor too, trying to find oil wells and map Earth’s surface. The results are useful lo science, but all that hammering probably gives ocean animal a headache.

As people realize how important sound is to ocean animals, they are looking for ways to reduce human noise. Ships could get quieter just by slowing down. Engineers are also trying to find quieter propeller ships.

Now some companies are using a simple invention called a bubble curtain, which makes sound waves passing through it lose energy and gel quieter. It seems to work - when bubble curtains were fixed on the San Francisco bridge project fish deaths dropped.

We still have a lot to learn about sound in the oceans, but together we can help keep the sea a quieter place.

1.Dolphins and whales arc mentioned to show       .

A. sound travels very well through water

B. they are surprisingly noisy in the sea

C. the ocean is filled with sound

D. ocean noise is a big problem

2.What is happening to ocean animals these days?

A. Human noise is causing danger to their safety.

B. There is less food in the ocean for them.

C. They are being killed in large numbers.

D. They are losing their hearing.

3.During the first repair to the bridge, some fish       .

A. started to die    B. were attracted to it

C. got quiet underwater    D. suffered from headaches

4.Bubble curtains are used to       .

A. research on fishes underwater    B. build the San Francisco bridge

C. stop noisy machines working    D. reduce construction noise