单项选择题

What can be inferred about the defense mechanisms of the sea cucumber

A．They are very sensitive to surrounding stimuli.
B．They are almost useless.
C．They require group cooperation.
D．They are similar to those of most sea creatures.

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热门试题

单项选择题

The fourth paragraph of the passage primarily discusses ______.

A．the reproduction of sea cucumbers
B．the food sources of sea cucumbers
C．the eating habits of sea cucumbers
D．threats to sea cucumbers' existence

单项选择题

The disappearance of old style hotel porters can be attributed to the fact that ______.

A．few people are willing to do this type of work
B．machines are more reliable than human beings
C．the personal touch is appreciated less nowadays
D．automation has provided cheaper alternatives