It was snowing hard and Mother told me to put on a thick coat to ______myself from the cold.

A．Prevent

B．save

C．explore

D．protect

用制备衍生物测熔点的方法鉴别盐酸丁卡因，加入的试液是

A．三硝基苯酚

B．硫酸铜

C．硫氰酸铵

D．三氯化铁

E．亚硝基铁氰化钠