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问题 单项选择题 A1型题

某3岁小儿，总是喜欢一个人玩耍，对父母似乎没有特别的感情，喜欢重复看特定的电视广告。经医生检查发现，其智力发育落后于一般儿童，但无语言发育障碍。其可能患有（）

A.阿斯伯格综合征

B.雷特综合征

C.儿童瓦解型精神障碍

D.儿童孤独症

E.心境障碍

答案

参考答案：D

单项选择题

羊水过多是指在妊娠任何时期羊水量超过

A．1000ml
B．1400ml
C．1600ml
D．1800ml
E．2000ml
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单项选择题

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.

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

A．oxygen

B．hydrogen

C．nitrogen

D．carbon dioxide
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