金属管道发生应力腐蚀破裂，其应力主要来自（）。
A.工作压力
B.载荷
C.冷加工及安装残余应力
D.焊接残余应力
参考答案：D
The essence of Zhang Method is the "theory of psychological advantage". It believes in the great ______ students have once they develop the right interest, enthusiasm and motivation in learning a foreign language.
有助于鉴别肌成纤维细胞和平滑肌细胞的标志物为（）
A.α-SMA
B.desmin
C.β-catenin
D.calponin
E.h-caldesmon
