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【多选题】
焊前预热的主要目的是（）A.
减少焊接应力
B.
提高焊缝强度
C.
有利于氢的逸出
D.
降低淬硬倾向
E.
提高耐腐蚀性
F.
防止冷裂纹
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参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】下列叙述正确的是
A.
标准状况下，l mol任何物质的体积均为22.4 L
B.
CH 4 的摩尔质量为16 g
C.
1mol H 2 O的质量为18 g?mol －１
D.
3.01×l0 23 个SO 2 分子的质量为32 g
【单选题】下列哪项不是肌力检查的目的
A.
判定被检查肌是否因疾病而受累以及受累程度
B.
根据综合肌群检查结果判断神经损伤平面
C.
为伤残鉴定提供参考依据
D.
为制订康复治疗方案提供依据
E.
为经济赔偿提供参考依据
【单选题】American Race to the Moon The roots of Americas plan to land a man on the moon can be found outside of the country. Although never directly mentioned in its official motto, the National Aeronautics an...
A.
remain mostly hidden.
B.
share similar origins.
C.
are found deep underground.
D.
can be hard to tell apart.
【单选题】Another technical advance in gardening in the 19th century was that people could grow plants in containers in spring and autumn only.
A.
Y
B.
N
C.
NG
【简答题】China’s High Speed Railway “High speed rail travel” has been called the most revolutionary means of transport of the late 20th century and early 21st century. Today, China’s high-speed railway or CRH,...
【单选题】American Race to the Moon The roots of Americas plan to land a man on the moon can be found outside of the country. Although never directly mentioned in its official motto, the National Aeronautics an...
A.
reasons.
B.
beginnings.
C.
successes.
D.
targets.
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