He had a good (occupation ) _______________ and occupies an office on his own.
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The shop (specialized) _____________ in mountain-climbing gear.
The heart disease has been one of the (fatal) _____________diseases to endanger the health and result in death.
代号为30212的滚动轴承内径宽度系列代号是（）
A. 0
B. 1
C. 2
D. 3
代号为6302的滚动轴承的内径是（）
A. 2
B. 10
C. 15
D. 不确定
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