He was ______ about his ______ son, who is always skipping classes.

A．worried, worried

B．worrying, worried

C．worried, worrying

D．worrying, worrying

2000年前的《神农本草经》就有麻黄能“止咳逆上气”的记载，它的结构简式为

下列说法正确的是(    )

A．麻黄的分子式为C₁₀H₁₇O

B．麻黄在空气中燃烧有NO释出

C．麻黄可以从植物中提取

D．麻黄的一溴代物有3种