呈圆盘状，直径3—6m，背部灰色或灰黑色，有白色环纹45—58个，背鳞扩大城六角形的中药是（）。
参考答案：金钱白花蛇
— How much should I pay for the food, Sir?
— It costs ______. The food is free on our ship. ______ needs to pay for it.
A．nothing; Nobody
B．none; Anybody
C．none; No one
D．nothing; Everybody
判断油罐切换成功的依据是（）。
