单项选择题
A.30° B.60° C.90° D.120°
A.5B.10C.15D.20
A.2.5′×2.5′ B.3.0′×3.0′ C.5.0′×5.0′ D.15′×15′
A.±8 B.±10 C.±12 D.±14
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