钢结构焊接质量无损探伤包括（）。

A.磁粉探伤

B.涡流探伤

C.渗透探伤

D.射线探伤和超声波探伤

He always ___________other people first.  [ ]

A. think of                    

B. thinks of    

C. thinks out                    

D. think over