待测粉末与氯仿共同振摇，过滤，水浴挥发至几乎干燥。（）
A．Shake the powder being examined with chloroform, filter and reserve the extracted powder.
B．Shake the powder being examined with chloroform, filter and evaporate almost to dryness on a water bath.
C．Heat the powder being examined with a mixture of water and hydrochloric acid in a water bath.
D．Heat the powder being examined to boiling with a mixture of ethanol and water.
E．Shake the powder being examined with sulphuric acid, filter and wash the filter with sulphuric acid.
