颅内压增高患者发生呕吐常出现在（）
A.清晨
B.夜间
C.餐后
D.头痛剧烈时
E.咳嗽时
参考答案：D
The machine is designed to people recycle wastes to a great degree but the result still remains to be seen. [ ]
A. aid
B. help
C. assist
D. improve
线性规划问题中基可行解与基解的区别在于（）
A.基解都不是可行解
B.基可行解变量Xj≥0
C.基解是凸集的边界
D.基解变量Xj≤0
ycle wastes to a great degree but the result still remains to be seen. [ ]