产生白点缺陷的外在原因是钢的（）过快使氢气不能充分逸出。
参考答案：冷却速度
Can you help _____ with _____ English? [ ]
A. he, his
B. his, his
C. him, his
D. him, him
列表比较缺血性结肠炎与溃疡性结肠炎的鉴别。
