氧化镁外形为（），比重3.2。

A.白色粉末；

B.白色疏松粉末；

C.灰白色粉末；

D.黄色粉末。

— Is your new team-mate a good guy? 

—  Yes. He is kind, skillful, hard-working and intelligent; ____, I can't speak too highly of him. [ ]

A. on the contrary

B. by the way

C. in a word

D. as a result