Part of Earth's beauty comes from its oceans． Ocean scientists study the chemical make﹣up of the ocean，weather patterns， the geography of the ocean floor， and many other areas． Their work is exciting，although sometimes dangerous． Using technology to do certain tasks helps．For example，robotic arms are used for very dangerous tasks．

    One basic part of ocean study is understanding waves and how they work．Wind is the great maker of waves． The waves we know are mostly produced by winds blowing over the sea． They are directly connected with the wind speed and the time that wind lasts．

    Sometimes ocean life can be seen in the wave．Living things seem to be staying within the wave，moving slowly inside it as if they were weightless．Besides the beauty of waves， scientists are interested in their technical ways． The diagram of waves shows how scientists examine waves． Waves are measured （测量）from the top （crest） to the bottom （trough）． This allows scientists to find out the height of a wave． They also measure waves from crest to crest to determine（测定）the length of a wave．

    During serious storms， huge waves might cut a sea ship apart． Ships are at great risk of winding up as broken pieces after being hit by the force of a huge wave． By understanding the ocean，scientists can prevent this breakup of ships by predicting when the water will be too dangerous for people and their ships． The study of waves and the ocean also allows scientists to make sure how certain beaches were formed． By studying the oceans， a great deal can be learned about the surface we live on．

（1）Why are robotic arms used？ Because　　．

A． certain tasks are very dangerous

B． the tasks are exciting

C． the oceans are beautiful

D． there are many studying areas

（2）What can we learn from the second paragraph？　　

A． Waves can make wind．

B． Most waves are produced by winds．

C． Scientists make most waves．

D． Waves have nothing to do with wind．

（3）What is the meaning of "the length of a wave" according to paragraph 3？　　

A． The beauty of huge waves．

B． The technical way to study the sea．

C． The distance from crest to crest of a wave．

D． The distance from the top to the bottom of a wave．

（4）Which of the following statements are right according to the passage？　　

①Scientists can decide the weather patterns．

②We can't find living things in the waves．

③By studying the ocean， scientists can prevent the breakup of ships．

④The study of waves helps scientists know how certain beaches were formed．

A．①③

B．②④

C．③④

D．②③

（5）Where is the passage probably from？　　

A． A diary entry．

B． A fairy tale．

C． A travel guide．

D． A science magazine．