阅读理解 The blue of the sea is caused by the scattering of sunlight by tiny particles suspended in the water. Blue light, being of short wavelength, is scattered more efficiently than light of longer wavelengths. Although waters of the open ocean are commonly some shade of blue, green water is commonly seen near coasts, especially in tropical or subtropical regions. This is caused by yellow pigments being mixed with blue water. Phytoplankton are one source of the yellow pigment. Other microscopic plants may color the water brown or brownish-red. Near the shore, silt or sediment in suspension can give water a brownish hue. Outflow of large rivers can often be observed many miles offshore by the coloration of suspended soil particles. Marine phytoplankton (Greek for "plant wanderers") are microscopic single-celled plants that include diatoms, dinoflagellates, coccolithophorids, green algae, and blue-green algae, among others. The growth of these organisms, which photosynthesize light, depends on a delicate balance of nutrient enrichment via vertical mixing, which is often limited by the availability of nitrogen and light. Diatoms are one-celled plants with patterned glass coverings. Each glass, or silicon dioxide box, is ornamented with species-specific designs, pits, and perforations making them popular with microscopists and, more recently, electron scanning microscopists.

单选题 Green water near coastlines is almost always caused by________.

【正确答案】 D

【答案解析】细节题型。见文章第一句：The blue of the sea is caused by the scattering of sunlight by tiny particles suspended in the water．蓝色的海水是由于阳光对悬浮于水中的微粒造成散射形成的。第四、五句：This is caused by yellow pigments being mixed with blue water．Phytoplankton are one source of the yellow pigment．海水呈绿色是由于蓝色的海水和呈现黄色的浮游生物混合形成的。所以选项D正确。

单选题 Phytoplankton are the source of which color pigment?

单选题 What can give waters a brownish hue near the shore?

单选题 Which of the following is NOT a type of phytoplankton?

【正确答案】 D

【答案解析】是非题型。见文章第二段第一句：Marine phytoplankton(Greek for“plant wanderers”)are microscopic single-celled plants that include diatoms，dinoflagellates, coccolithophorids，green algae，and blue-green algae，among others．说明海洋浮游生物包括：A．Green algae绿藻；B．Diatoms硅藻属；C．Blue-green algae蓝绿藻；等等。选项D．“Amoeba阿米巴虫”不包括在内，所以是答案。

单选题 The growth of phytoplankton is often limited by the availability of________.

【正确答案】 C

【答案解析】细节题型。见文章第二段第二句：The growth of these organisms，which photosynthesize light，depends on a delicate balance of nutrient enrichment via vertical mixing，which is often limited by the availability of nitrogen and light．所以选项C正确。