They're all wearing mortarboards and you can't see his face.
他们都戴着学位帽，你看不到他的脸。
2
You have a built-in cap, and I'm not referring to the mortarboards on your heads.
你们戴了一顶内置的帽子——我并不是指你们戴在头上的那顶学位帽。
3
Faces were somber as the dean commemorated the dead, but graduates broke out in cheers and tossed their mortarboards in the air as the ceremony concluded.