A.先開(kāi)助燃?xì)?,后關(guān)助燃?xì)?br /> B.先開(kāi)燃?xì)?,后關(guān)燃?xì)?br /> C.后開(kāi)助燃?xì)?,先關(guān)助燃?xì)?br /> D.后開(kāi)燃?xì)?,先關(guān)燃?xì)?/p>
A.手捏比色皿毛面 B.可見(jiàn)-紫外分光光度計(jì)開(kāi)機(jī)后馬上就進(jìn)行測(cè)量 C.測(cè)定蒽醌含量時(shí),必須打開(kāi)分光光度計(jì)的氘燈 D.測(cè)定液體化學(xué)品的色度時(shí),沿比色管軸線方向比較顏色的深淺