剧烈频繁呕吐可引起（）
A.呼吸性酸中毒
B.呼吸性碱中毒
C.代谢性酸中毒
D.代谢性碱中毒
E.混合性酸中毒
参考答案：D
骨关节CT检查，一般采用（）
A.平扫加增强扫描
B.仰卧患侧横轴位
C.定位像代替平片
D.俯卧双侧横轴位
E.骨窗和软组织窗并双侧骨关节对比观察
An oligopolistic firm:（）
A. will consider the potential response of its rivals when making business decisions.
B. is likely to be formed when the minimum-cost output is only a small portion of the market output.
C. is likely to be formed when barriers to entry are low.
