用1151差变测量流量,差压范围为0--20KPa,流量范围0--16Nm3/h,则当显示的流量为8Nm3/h时,测得的差压为()。
A.5
B.8
C.10
D.12
参考答案:A
请若(x+y)(1-x-y)+6=0,则x+y的值是______
— You ought to have called her yesterday .
— Yes , I know I ____ .
A.ought to
B.ought to have
C.ought have done
D.ought to have called