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
