Energy goes from one plant or animal to another. A food chain shows how this energy moves. Each time an animal gets eaten, its energy is passed onto the animal that eats it. The food chain is very important because it keeps the balance of nature. If one part of the food chain disappears, it can affect all the other plants and animals. Any threat to the food chain is a threat to the environment’s biodiversit(生物多样性). The food chain helps keep animal populations in balance. However, if something happens to increase or decrease one of the links in the food chain, that balance is broken. If one animal becomes endangered, it puts all the animals above it at risk.
Some of the threats are natural, such as wildfires, hurricanes, tornados, floods and so on. But the biggest threats to the food chain come from you and me. These threats include overhunting, overfishing, logging, farming, development, pollution, etc. The food chain is endangered anywhere humans have had an effect on the natural environment.
A recent study shows that the overfishing of large sharks is damaging the food chain along the US Atlantic coast. Canadian and American scientists say sharks are being killed in great numbers for their meat and fins(鳍). Now, not enough sharks are around to eat the cownose(牛鼻) ray. The ray’s population has increased and they have eaten up the shellfish to the point where it has hurt commercial(商业的) fishing.
Many of us disturb the natural environment in our own backyards. It’s up to us to take care of the environment and try not to disrupt the natural food chain. If we don’t act responsibly, animals will start disappearing.
What can we learn from Paragraph 1?

A．The food chain is not easy to be broken.

B．The energy of an animal usually disappears when it dies.

C．Increasing the links will not break the balance of nature.

D．Breaking the food chain is bad for the biodiversity of the environment.

The study mentioned in Paragraph 3 proves that            .

A．human activities can be a big threat to the food chain

B．we are all responsible for the breaking of the food chain

C．natural disasters are hard to break the food chain

D．hunting large sharks for meat is beneficial

We can infer that the writer wrote this passage mainly to           .

A．explain what the food chain is

B．tell us something interesting about Nature

C．suggest that we stop eating meat to save animals

D．suggest that we not disrupt the natural food chain