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【单选题】Passage 3 Questions 11 to 15 are based on the following passage: Scientists in India have invented a new way to produce electricity. Their invention does not get its power from oil, coal or other fuel...
A.
Because bullocks have long been used by Indian people
B.
Because bullocks walk slowly and are easy to control.
C.
Because there are few non-working bullocks in India
D.
Because there is not enough oil in India.
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【单选题】Passage 3 Questions 11 to 15 are based on the following passage: Scientists in India have invented a new way to produce electricity. Their invention does not get its power from oil, coal or other fuel...
A.
Because bullocks have long been used by Indian people
B.
Because bullocks walk slowly and are easy to control.
C.
Because there are few non-working bullocks in India
D.
Because there is not enough oil in India.
【单选题】齿轮的润滑主要靠（）
A.
边界油膜
B.
刚性油膜
C.
弹性油膜
【单选题】两带轮的传动比i＞1，是()传动
A.
增速
B.
减速
C.
变速
【单选题】3 带的弹性滑动使传动比
A.
不恒定
B.
恒定
C.
平均恒定
【单选题】图示轮系中，已知z1=28，z2=25，z3=70， z3’=30，z4=36，求轮系传动比i14。
A.
8
B.
16
C.
12
D.
3
【多选题】开式齿轮的主要失效形式是__。
A.
轮齿折断
B.
齿面磨损
C.
齿面胶合
D.
齿面点蚀
【单选题】齿轮的渐开线形状取决于它的（）直径。
A.
齿顶圆
B.
分度圆
C.
基圆
D.
齿根圆
【判断题】自动变速器中的齿轮都是行星齿轮。()
A.
正确
B.
错误
【单选题】如图,已知:Z1=28,Z2=42,Z3=32,Z4=48,(Z为齿数)其传动比为( )
A.
1
B.
2.5
C.
3
D.
3.25
【单选题】只要（）的齿轮就能互相啮合。
A.
齿数和模数相同
B.
模数和压力角相同
【单选题】齿轮传动比最好是( )。
A.
有理数
B.
无限循环有理数
C.
无理数
D.
整数
【单选题】SS4改电力机车的传动比是（）
A.
88/21
B.
88/22
C.
88/23
D.
88/24
【单选题】直接档传动比为()。
A.
＞1
B.
＜1
C.
＝1
D.
随转速而定