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【单选题】
锪孔时存在的主要问题是锪钻的震动，使用钻头修磨锪钻要尽量选择（）钻头。
A.
A、短
B.
B、长
C.
C、粗
D.
D、耐震动
参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【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