Cho tứ diện ABCD có AB=AC=2, DB=DC=3. Khẳng định nào sau đây đúng?

A.  B C ⊥ A D

B.  A C ⊥ B D

C.  A B ⊥ B C D

D.  D C ⊥ A B C  

Over the years, he gradually became impervious _________ about his wife’s comments about his chosen profession and in the end she stopped complaining.

A. about

B. for

C. of

D. to