苏木中易被氧化成红色的成分是（）
A.巴西苏木素
B.原苏木素A
C.苏木酚
D.挥发油
E.黄酮类
参考答案：A
用数字和符号表示填空：
氯元素______，3个氮原子______，4个铝原子______，2个氧气分子______，2个钠离子______，5个水分子______．
The shop-assistant was straight with his customers. If an article was of _____ quality, he'd tell them so.
A．humble
B．minor
C．inferior
D．awkward
