地图上一般方向为（ ）
A．上北下南左西右东
B．上南下北左西右东
C．上东下西左北右南
D．一般根据指向标
答案：A
焦炭水分稳定，有利于高炉生产。
Which of the following statements concerning liver sinusoids is TRUE
A． They are continuous with bile canaliculi
B．They are surrounded by a well developed basal lamina
C．They are lined by nonfenestrated endothelial cells
D．They deliver blood to the central vein
E．They deliver blood to portal vein
