[单项选择]
Sharks Perform a Service for Earth’s Waters
It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to
(51) people frequently. But these fish perform a
(52) service for earth’s waters and for human beings. Yet business and sport fishing are threatening their
(53) . Some sharks are at risk of disappearing from
(54) .
Warm weather may influence both fish and shark activity. Many fish swim near coastal areas
(55) their warm waters. Experts say sharks may follow the fish into the same areas,
(56) people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person
(57) a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or comes up. Those are the
(58) when sharks are looking for food. Experts also say that bright colors and shiny jewelr
A. feelings
B. senses
C. touches
D. tastes
