B
By the end of the century, if not sooner, the world's oceans will be bluer and greener thanks to a warming climate, according to a new study.
At the heart of the phenomenon lie tiny marine microorganisms (海洋微生物) called phytoplankton.Because of the way light reflects off the organisms, these phytoplankton create colourful patterns at the ocean surface.Ocean colour varies from green to blue, depending on the type and concentration of phytoplankton.Climate change will fuel the growth of phytoplankton in some areas, while reducing it in other spots, leading to changes in the ocean's appearance.
Phytoplankton live at the ocean surface, where they pull carbon dioxide (二氧化碳) into the ocean while giving off oxygen.When these organisms die, they bury carbon in the deep ocean, an important process that helps to regulate the global climate.But phytoplankton are vulnerable to the ocean's warming trend.Warming changes key characteristics of the ocean and can affect phytoplankton growth, since they need not only sunlight and carbon dioxide to grow, but also nutrients.
Stephanie Dutkiewicz, a scientist in MIT's Center for Global Change Science, built a climate model that projects changes to the oceans throughout the century.In a world that warms up by 3 ℃， it found that multiple changes to the colour of the oceans would occur.The model projects that currently blue areas with little phytoplankton could become even bluer.But in some waters, such as those of the Arctic, a warming will make conditions riper for phytoplankton, and these areas will turn greener.“Not only are the quantities of phytoplankton in the ocean changing”， she said, “but the type of phytoplankton is changing.”
And why does that matter? Phytoplankton are the base of the food web.If certain kinds begin to disappear from the ocean，Dutkiewicz said, “it will change the type of fish that will be able to survive.” Those kinds of changes could affect the food chain.
Whatever colour changes the ocean experiences in the coming decades will probably be too gradual and unnoticeable, but they could mean significant changes.“It'll be a while before we can statistically show that the changes are happening because of climate change.” Dutkiewicz said, “but the change in the colour of the ocean will be one of the early warning signals that we really have changed our planet.”
文章大意：本文是一篇说明文。调查表明，由于气候变暖，全球的海洋将会变得更蓝、更绿。
24．What are the first two paragraphs mainly about？__B__
A．The various patterns at the ocean surface.
B．The cause of the changes in ocean colour.
C．The way light reflects off marine organisms.
D．The efforts to fuel the growth of phytoplankton.
解析：段落大意题。文章第一段点题：由于气候变暖，全球的海洋将会变得更蓝、更绿。第二段介绍由于光从生物体反射的方式，这些浮游植物在海洋表面形成了五颜六色的图案；气候变化又使得这些浮游植物在某些区域加速生长而在其他地方有所减少，导致海洋表面的颜色变化。由此可知前两段讲了海洋颜色变化的原因。故B项正确。
25．What does the underlined word “vulnerable” in Paragraph 3 probably mean？__A__
A．Sensitive. B．Beneficial.
C．Significant. D．Unnoticeable.
解析：词义猜测题。后一句提到，气候变暖改变了海洋的主要特点并能影响浮游植物的生长，因为它们要生长不仅仅需要阳光和二氧化碳，也需要营养。由此可知，这些浮游植物对海洋变暖很敏感。故A项正确。
26．What can we learn from the passage？__D__
A．Phytoplankton play a declining role in the marine ecosystem.
B．Dutkiewicz's model aims to project phytoplankton changes.
C．Phytoplankton have been used to control global climate.
D．Oceans with more phytoplankton may appear greener.
解析：细节理解题。由文章第四段信息“But in some waters，such as those of the Arctic，a warming will make conditions riper for phytoplankton，and these areas will turn greener.”可知浮游植物多的区域海水会变得更绿。故D项正确。
27．What is the main purpose of the passage？__C__
A．To assess the consequences of ocean colour changes.
B．To analyse the composition of the ocean food chain.
C．To explain the effects of climate change on oceans.
D．To introduce a new method to study phytoplankton.
解析：主旨大意题。文章主要论述了随着气候变暖，全球的海洋将会变得更蓝、更绿，即气候变化对海洋有影响。故C项正确。
