在质量为M的电动机飞轮上固定着一个质量为m的重物,重物到转轴的距离为r,如图所示

题型:选择题

问题:

在质量为M的电动机飞轮上固定着一个质量为m的重物,重物到转轴的距离为r,如图所示,为了使放在地面上的电动机不会跳起,电动机飞轮的角速度不能超过(  )

A.

M+m
mr
g

B.

M+m
mr
g

C.

M-m
mr
g

D.

Mg
mr

考点:向心力牛顿第二定律
题型:选择题

下列关于主动脉病变X线表现,错误的是()

A.主动脉位置改变

B.主动脉狭小

C.主动脉外形不规则

D.主动脉增宽,伸长和迂曲

E.以上都不是

题型:选择题

They went on working _______ it was very late. [ ]

A. than

B. if

C. though

D. because

题型:选择题

* * 的紫红或紫蓝色结节一般见于()。

A.子宫体癌

B.绒毛膜癌

C.恶性淋巴瘤

D.侵袭性(恶性)葡萄胎

E.子宫颈癌

题型:选择题

对硬铝合金制件最好在完成下列哪项工序之后,立即进行机械加工?()

A.加热。

B.阳极化处理。

C.淬火。

D.时效处理。

题型:选择题

An analyst does research about the impact of tax rate changes on a company's financial statements. For existing deferred tax assets and liabilities, an increase in income tax rate:

A. increases both deferred tax assets and deferred tax liabilities.
B. decreases both deferred tax assets and deferred tax liabilities.
C. decreases deferred tax assets and increases deferred tax liabilities.

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