涂装车间作业环境主要防范（）。
A、噪声
B、火源
C、防水
参考答案：B
—Oh, must you leave? Having dinner with you was such ______ fun.
—Thanks all the same, but I have to make ______ early start tomorrow morning.
A．/; an
B．a; an
C．/; the
D．a; the
钢铁发生吸氧腐蚀的时候，发生还原反应的电极方程式是
A．Fe－2e－==Fe2+
B．2H＋＋2e－==H2 ↑
C．4OH－－4e－==2H2O＋O2↑
D．2H2O＋O2＋4e－==4OH－
