上消化道出血最常见和有特征性的症状和体征为()
A.呕血及黑便
B.腹痛
C.腹泻
D.恶心、呕吐
E.黄疸
参考答案:A
钢结构工程中应检查复验报告的项目有()。
A.混批钢材
B.焊接球
C.高强螺栓
D.连接用紧固标准件
E.主要受力构件焊接材料
A survey done recently show that not all parents _____ their children taking part in the weekend classes. [ ]
A. escape
B. lead to
C. imagine
D. approve of