题目内容：

All living things must fight to stay alive. They have to feed on something and at the same time avoid being eaten. Therefore they have to solve this big problem of staying alive in their own way.

The danger of being eaten in the sea is great. Those plants and animals that do survive usually reproduce very fast and in great numbers.

Certain sea animals have defensive devices(装置) which help them to survive. The jelly fish have poisonous tentacles(触角) which are used for attack and defence.

Another method of survival which sea plants and animals use is disguise(伪装). They usually have the same color as their surroundings.

In order to stay alive, animals need to have good senses. Fishes have sharp eyes. Almost all animals are sensitive to touch. Fishes judge movements in the water by means of their lines. Fishes and other sea animals can hear well and many of them can make different types of warning sound.

1.What is the greatest problem that the living things face?(no more than 10 words)

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2. How many ways that animals in the sea survive are mentioned (提到)（no more than 2 words）?

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3.What do the jelly fish have to protect themselves from being attacked?(within 15 words)

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4.What does the word "survive" in the second paragraph mean?(no more than 6 words)

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5.List at least two methods of helping animals survive.(no more than 15 words)

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