A．用锌和稀硫酸制取氢气
B．用双氧水和二氧化锰制取氧气
C．用高锰酸钾加热分解制取氧气
D．用石灰石和稀盐酸制取二氧化碳
答案：C
They asked the students ______ as soon as possible. [ ]
A. answered
B. to reply
C. answering
D. replying
“天线”的业余无线电通信常用缩语是（）
A.ANT
B.ATT
C.ATN
D.ATR
