单项选择题
A.两行坩埚中央 B.离炉膛底20~30mm C.炉膛中央 D.离炉膛底10~20mm
A.6min,(815±10)℃ B.6min,(850±10)℃ C.7min,(820±10)℃ D.7min,(850±15)℃
A.(50±2)r/min B.(50±1)r/min C.(100±2)r/min D.(100±1)r/min
A.0.1mg B.0.2mg C.0.01g D.1mg
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