幽门螺杆菌的主要传播途径有（）
A.空气传播
B.液传播
C.粪-口传播
D.母婴传播
E.密切接触
参考答案：C, E
The workers will go on strike if the demands they ________ are turned down.[ ]
A. put aside
B. put through
C. put forward
D. put away
寿命周期成本
