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【多选题】
图书馆电子数据库中有的文献不能下载是什么原因A.
没在校园网 IP 内上网进行下载或者没有选择校园网的登陆选项
B.
每个数据库平台上有很多子库, 我校可能只购买了数据库当中的读者利用率较高的一部分子库
C.
较早的文献没有被电子化, 电子数据库中检索不到
D.
网络故障或是数据库正在进行维护
拍照语音搜题，微信中搜索"皮皮学"使用
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】One method of determining crankshaft misalignment is by（）
A.
laying a straight edge across the crank webs at the crankpin and measuring the distance to the crankpin in two places
B.
measuring the crank drop on either side of each crank throw while the crankshaft is slowly rotated through one revolution
C.
rotating the crankshaft through one revolution, pausing each 90oof rotation to measure bearing clearances, top and bottom
D.
taking micrometer reading between the crank cheeks opposite the crankpin every 90°of crank angle rotation
【单选题】In a four-stroke/cycle diesel engine, the camshaft rotates at _____.
A.
twice the crankshaft speed
B.
half the crankshaft speed
C.
the same speed as that of the crankshaft
D.
a speed independent of that of the crankshaft
【单选题】在贮存和使用易燃液体的区域必须要有良好的通风条件, 其主要目的是为了。
A.
)
B.
防止易燃气体积聚而发生爆炸和火灾
C.
冷却易燃液体
D.
保持易燃液体的质量
E.
令使用者身心舒畅
【单选题】The camshaft drive is designed to maintain proper camshaft speed relative to crankshaft speedIn maintaining this relationship, the camshaft drive causes the camshaft to rotate at .
A.
one half crankshaft speed in a two-stroke cycle diesel engine
B.
crankshaft speed in a two-stroke cycle diesel engine
C.
two times crankshaft speed in a two-stroke cycle diesel engine
D.
one-fourth times crankshaft speed in a four-stroke cycle diesel engine
【简答题】crankshaft
【单选题】在下列各式中正确的个数是( ) 11∈{0,1,2};2{1}∈{0,1,2};3{0,1,2}⊆{0,1,2};4{0,1,2}={2,0,1}
A.
1
B.
2
C.
3
D.
4
相关题目：
【单选题】在贮存和使用易燃液体的区域必须要有良好的通风条件, 其主要目的是为了。
A.
)
B.
防止易燃气体积聚而发生爆炸和火灾
C.
冷却易燃液体
D.
保持易燃液体的质量
E.
令使用者身心舒畅