亲子关系、同伴关系、亲社会行为等内容都属于（）。
A.认知发展
B.社会性发展
C.自我意识的发展
D.个性发展
参考答案：B
Thousands of houses by the floods in Guangxi last month.
A. destroy
B. destroyed
C. have destroyed
D. were destroyed
氩弧焊的安全注意事项有哪些？
