试述声级计的种类、组成和作用。

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问题:

试述声级计的种类、组成和作用。

考点:机电设备评估基础设备状态监测与故障诊断技术设备状态监测与故障诊断技术题库
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下图为绿色植物的生理活动示意图,请据图回答:

(1)从叶的结构来看,物质a、b是通过_______进出叶片的。

(2)若此图表示光合作用过程,则a代表的物质是____________,d代表的物质是________,c物质在植物体内上升的动力主要来自_______作用。

(3)若此图表示呼吸作用过程,则a代表的物质是________,b代表的物质是__________。

(4)若植物表现为生长现象,则其光合作用过程________呼吸作用过程 (填“大于” “小于”或“等于”)。

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下列各种营养物质中,可以不经消化直接就被吸收的是(  )

A.淀粉

B.蛋白质

C.脂肪

D.无机盐

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Certificates are (71) documents attesting to the (72) of a public key to an individual or other entity. They allow verification of the claim that a given public key does in fact belong to a given individual. Certificates help prevent someone from using a phony key to (73) someone else. In their simplest form, Certificates contain a public key and a name. As commonly used, a Certificate also contains an (74) date, the name of the CA that issued the Certificate, a serial number, and perhaps other information. Most importantly, it contains the digital (75) of the certificate issuer. The most widely accepted format for certificates is X.509, thus, Certificates can be read or written by any application complying with X.509.

73()

A.impersonate

B.personate

C.damage

D.control

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* * 有大量白色稠厚豆渣样白带,最可能的疾病是()。

A.念珠菌性 * * 炎

B.滴虫性 * * 炎

C.慢性宫颈炎

D.子宫内膜炎

E.输卵管炎

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为什么制造腊模时采用糊状腊料加压成形,而较少采用腊液浇注成型?为什么脱蜡时水温不应到沸点?

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