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【单选题】
增加抽油机井的动载荷，引起杆柱和地面设备的强烈震动，容易损坏设备的是()。
A.
小泵径
B.
长冲程
C.
短冲程
D.
快冲次
参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】自动扶梯连续运行时间每天不应少于（ ）h,每周不应少于（ ）h,每3h能以100%制动载荷连续运行1h。
A.
18;140
B.
20;140
C.
18;160
D.
20;160
【单选题】The Grand Canyon Standing on the rim of the Grand Canyon(大峡谷), gazing across this giant wound in the Earth’’s surface, a visitor might assume that the canyon had been caused by some ancient convulsion...
A.
it was caused by some ancient convulsion
B.
its presence is an embarrassment to the state of Colorado
C.
it looks like an injury on the Earth’s surface
D.
it has caused many visitors to injure themselves