下列可用于土壤消毒来防治苗木立枯病的是（）。
A．五氯硝基苯
B．代森锌
C．生石灰
D．多菌灵
参考答案：A, C
—Sorry, I have to ring ________ now. It's time for class.
—OK, I'll call back later.
何谓“三丝“？
