题目内容：

To me, the ocean is our greatest wilderness. I love swimming in it , surfing its waves, watching it from shore and thinking about all the life living unseen under the surface.

When I take my little kids to check out tide pools, we’re overjoyed when we find a sea star or some shellfish. Lately, though, I've noticed a change in my favorite pools: there are more sea grasses and fewer animals with shells.

I can't help feeling these small changes portend something more troubling about our oceans. It matches what scientists are telling us: our oceans are being troubled by carbon dioxide that threatens corals, colorful fish, salmon, sea otters, even whales. Our oceans are facing a major change.

Every hour, a million tons of carbon dioxide from cars, factories and power plants rain down on the world’s oceans. Carbon pollution brings about a chemical reaction that turns sea water more acidic (酸的) and takes away things important for sea animals .

Some of us are already feeling the effects of this growing crisis（危机）. Shellfish farmers in the Pacific Northwest have reported a decrease in natural and farmed oysters(牡蛎). Just this week, a new studyproved the link between the huge reduction in the numbers of oysters and ocean acidification. As polar waters become more acidic, Alaskan fishermen are troubled by the future of smaller fish.

Without action, ocean acidification will have a disastrous influence on the food chain, affecting not only sea life but the people who depend on it for food and their living. Already, our oceans have become 30 percent more acidic since preindustrial times, and it gets worse every day. We can stop this frightening dream, but only if we act now.

That's why the Center for Biological Diversity has started a petition (请愿书) requesting President Obama and the Environmental Protection Agency to develop a plan to deal with ocean acidification. Decisive action can save sea life as we know it.

Now it isn’t too late to save our oceans and sea life. With immediate action to reduce carbon dioxide release we can start taking important steps today to deal with this disastrous situation. Join me in our petition calling for a national plan to save our oceans.

1.The author’s recent visits to the tide pool brought her ___ .

A．happiness         B．anger             C．concern          D．comfort

2.The underlined word “portend” in Paragraph 3 probably means ___ .

A．predict           B．prevent           C．replace           D．reduce

3.What the author worries about most is ____ .

A．the harm of sea grasses

B．carbon pollution in the sea

C．that the petition may be turned down

D．how fishermen can make a living in the future

4.What is the main purpose of the text ?

A．To inform.         B．To educate.        C．To persuade .       D．To instruct.