When dry chemical extinguishers are used to put out class B fires，there is a danger of reflash because dry chemical（）.

A.is not an effective agent on Class B fires

B.does little or no cooling

C.dissipates quickly

D.is rapidly absorbed by the liquid

男，31岁，发热伴牙龈出血1周。查体：贫血貌，脾肋下3cm，胸骨压痛（+），血红蛋白65g/L，白细胞16×10⁹/L，血小板35×10⁹/L，骨髓增生明显活跃，原始细胞占0.62，为迸一步诊断，应首选哪项检查（）

A.染色体核型分析

B.细胞化学染色

C.血清铁测定

D.血细菌培养

E.抗血小板抗体检测