风心病患者保持适当活动对身体的好处是()
A.可防止双下肢静脉血栓形成
B.增加冠状动脉侧支循环
C.保持肌肉功能
D.防止便秘
E.延缓心瓣膜进一步损害
参考答案:A, B, C, D
—Where is your father? We haven't seen each other for weeks.
—______. [ ]
A. He has gone to England
B. He is going to America
C. He would visit my grandparents
D. He has been to America
OA的含义是()。
A.政府上网
B.办公自动化
C.政府信息化
D.电子商务