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问题 选择题

下列变化可用质量守恒定律进行解释的是（　　）

A．10g水变成10g冰

B．物质升华时要吸收热量

C．9g水完全电解生成lg氢气和8g氧气

D．5g糖放入25g水中得到30g糖水

答案

A、B、D选项中 物质均没有发生化学变化，故不能用质量守恒定律来解释．

    C、水电解生成氢气和氧气，发生了化学变化，故可用质量守恒定律来解释．

  故选C．

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.

Which of the following is NOT a type of phytoplankton

A．Green algae.

B．Diatoms.

C．Blue-green algae.

D．Amoeba.
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问答题 简答题

非法收购盗伐、滥伐珍贵树木4.5立方米是否属于情节特别严重？
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