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问题 单项选择题 A1/A2型题

血清游离镁约占血清镁（）.

A.1/2

B.1/3

C.1/4

D.1/5

E.1/10

答案

参考答案：A

解析：血清镁中游离镁约占55%，镁盐15%，与蛋白结合镁30%.

单项选择题

与粗出生率计算公式分母相同的指标是

A．婴儿死亡率

B．新生儿死亡率

C．粗死亡率

D．总生育率

E．生存率
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填空题

Recycling Paper


The process of recycling paper can help to reduce deforestation and energy consumption on a significant scale. There are many different reasons why we should recycle paper products, and some of these are (26) in the paragraphs below.
Energy consumption will always be on the (27) as population levels grow, and so any manufacturing processes which help to reduce energy consumption are (28)
The Energy Information Administration (EIA) claim that there can be as (29) as a 40% energy saving when recycling paper over producing paper (30) the direct raw material.
Although recycling paper has many (31) , it also has its drawbacks. One of these drawbacks is that we cannot recycle the (32) paper product for eternity, as the fibers contained within the paper degrade over time, (33) their strength and length.
On (34) , an individual paper fiber can only be recycled a (35) of six times. Although this is a significant drawback, the six time recycling process will help to (36) a great deal of energy when you consider (37) much paper there is to be recycled.
If paper fibers can be recycled up to 6 times, and we recycled all paper products, this could help to (38) the intensity of deforestation for paper products up to a factor of 6.
With paper production said to (39) around 40% of harvested wood, and paper said to (40) around 90% wood, you can see how recycling paper is an important process for the (41) of our forests.
Today, the use of recycled paper products is on the increase, as more and more people begin to recycle paper (42) products around the home.
Although there are slight differences in the recycling processes of different (43) of paper products (e.g. corrugated, mixed paper, newspaper products), we are able to recycle just about any type of paper product around today.
The recycling logo helps to (44) a recyclable product and can also sometimes help to identify if the product contains any recycled material, in the form of a percentage. This helps a consumer to identify the (45) of recycling various products.

A. fall B. rise C. top D. surface
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