冷裂纹产生的原因主要有:钢材的淬火倾向、()、焊缝金属和向热影响区扩散()。
参考答案:残余应力、氢含量
与东南部相比,西部牧业灾害具有更大的风险和更重的灾情是因为西部地区
①草原面积广阔、经济落后②经营粗放,靠天养畜③自然灾害种类多样④农业受灾体脆弱 [ ]
A、①②
B、②③
C、③④
D、①③
Our English teacher, as well as all the students, we can only improve our reading by reading widely.
A.agree that
B.agrees that
C.agrees with what
D.agree what