安装孔板时,如何确定正负压室,小孔起什么作用?小孔向上还是向下?
参考答案:倒角一侧为负压室,不倒角一侧为正压室。(没有倒角看标牌)小孔为液流孔,小孔向下。
It was at the very beginning ______ Mr Smith made a decision _____we should send for a doctor.
A.when; which
B.that; which
C.when; that
D.that; that
用图8-4回答。
如果对这个市场上的产品收税,总剩余的面积是()
A.A+B+C+D
B.A+B+C+D+E+F
C.B+C+E+F
D.E+F
E.A+D