为保证空气预热器的气动电动机能自动启动，必须使供气管路上的（）保持开启状态。
参考答案：手动
下列反应中，属于氧化还原反应的是
A．Cl2 + 2NaOH =" NaCl" + NaClO + H2O
B．2Br－ + Cl2 = 2Cl－ + Br2
C．CaCO3 + 2HCl = CaCl2 + H2O + CO2↑
D．2CO2 + 2Na2O2 = 2Na2CO3 + O2↑
-Turn off the TV, Jack.___________ your homework now?
-Mum, just ten more minutes, please. [ ]
A. Should you be doing
B. Shouldn't you be doing
C. Couldn't you be doing
D. Will you be doing
