单项选择题
A.等于 B.大于 C.小于
A.2a+50mm B.5a+50mm C.5a+100mm D.5a+150mm
A.d+2a B.d+2.5a C.(d+2.5A.±0.5a
A.1:1 B.1:2 C.2:1 D.1:3
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