题干
The sea is home to billions of plants and animals. Many live only near the sunlit surface. Oceanographers sort marine (海洋的) living beings by dividing them into two main groups: plants and animals.
There are two general types of plants found in the ocean, those having roots that grow in the ocean bottom and those not having roots which simply float around with water. The rooted plants in the ocean are only found in shallow waters because there is not enough sunlight to maintain photosynthesis (光合作用) in deeper waters. Since sunlight does not pass more than a few hundred feet into the ocean, most of the ocean is unable to support rooted plants.
The most plants in the ocean are known as phytoplankton (浮游植物群落) . These are usually single-celled, small floating plants that float throughout the surface waters of the ocean. To grow, phytoplankton need nutrients from the sea water and lots of sunlight.
Marine animals are divided into three groups: zooplankton, nekton, and benthos. Zooplankton are floating animals and are usually small; however, they can grow to fairly large size. The jellyfish and the Portuguese man-of-war are examples of larger types of zooplankton which are unable to move themselves effectively.
Nekton are the free swimmers and probably the largest part of familiar animals found in the ocean belong to this class. Common fishes, octopuses, whales, eels and squid are all examples of nekton.
The third type of sea animals spends their entire life on the bottom of the ocean. This group of marine animals is called benthos. Some of these creatures, such as lobsters and snails, may be able to move about on the bottom but their lifestyle is so closely linked with the ocean floor that they are unable to survive away from this environment.
【小题1】What does the text mainly introduce?| A．Marine plants and marine animals. | B．Two types of sea plants. |
| C．Three kinds of sea animals. | D．Small and big animals in the ocean. |
| A．Because there are too many rocks at the bottom of the ocean. |
| B．Because the rooted plants can’t stand the coldness of the ocean. |
| C．Because there is not enough sunlight for them in deep waters. |
| D．Because the rooted plants need more sunlight than plants which have no roots. |
| A．they are small and never grow to large size |
| B．some of the zooplankton can’t swim quickly |
| C．they can swim freely in deep waters of the ocean |
| D．they need more sunlight than other animals in the ocean |
| A．benthos live on the surface of the ocean water |
| B．some of the benthos can’t live without the ocean floor |
| C．benthos spend most of their time swimming in the ocean |
| D．benthos can move about in the middle of the sea water |
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