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【单选题】
截面工件发生铰折时，弯曲的上表面和下表面所受到的力分别是A.
上表面受压力，下表面受拉力
B.
上表面受压力，下表面受压力
C.
上表面受拉力，下表面受压力
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举一反三
【单选题】Years ago, many of the machines were operated ______ but now they are operated by computers.
A.
manually
B.
artificially
C.
automatically
D.
synthetically
【单选题】In the deserted factory several huge machines were left to rust and decay.
A.
inaugurate
B.
disintegrate
C.
accelerate
D.
disseminate
【单选题】It was in this factory ______ 'West Lake' sewing machines were made.
A.
where
B.
that
C.
in which
D.
there
【简答题】断路器控制和信号回路有哪些主要要求?
【单选题】The keys of Sholes' first typing machines were likely to be twisted together.
A.
Y
B.
N
C.
NG
【单选题】A number of new machines were introduced from abroad，______ an increase in production.
A.
resulted in
B.
to result in
C.
result in
D.
resulting in
【单选题】The earliest bicycles were called 'running machines' because ______.
A.
people have to run on feet when using the machines
B.
they were faster than running men
C.
the riders could run on the bicycles
D.
the bicycles could run fast automatically
【单选题】______ of the machines on display were made in China.
A.
Second-fifths
B.
Two-fifth
C.
Two-fifths
D.
Second-fifths
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