1＋1,2＋3,3＋5,1＋7,2＋9,3＋11,1＋13，…第40项为( )
A．1＋83
B．1＋81
C．1＋79
D．1＋77
参考答案：C
--Have you turned off the light?—Sorry, I ___ all about it.
A．have forgotten
B．forgot
C．had forgotten
D．would forget
炉水磷酸根不合格的可能原因有哪些？
