以下选项中()属于同时凝固原则的优点。
A.各部分冷却均匀
B.铸件不容易产生变形和裂纹
C.冒口补缩作用好,铸件内部致密
D.热应力小
参考答案:A, B, D
—Why didn't Mary see me wave (挥手) to her?
—She ________ in the other direction.[ ]
A. looked
B. has looked
C. was looking
D. is looking
女患,28岁,以"跳舞时出现剧烈头痛、呕吐2小时"为主诉入院。查体:神清语利,肢体无瘫痪,颈强直(+)、双Kernig征(+)。应首先作何种辅助检查来确定诊断()
A.脑电图
B.脑超声血流
C.脑动脉造影
D.腰穿
E.头颅CT