小剂量亚甲蓝治疗（）
A.有机磷中毒
B.铅中毒
C.氰化物中毒
D.亚硝酸盐中毒
E.急性酒精中毒
参考答案：D
— May I ___________ Helen?
— This is Helen speaking.[ ]
A. speaking
B. speak
C. speak to
D. to speak
I would rather ____ to the party than ______at home.
A．go; to stay
B．to go; stay
C．go; stay
D．to go; to stay
