A negative face has an outward normal pointing in a direction opposite that of the positive x-axis.

负向的外法线指向与正x轴相反的方向。

youdao

I had to sleep face down for the first month to give the "buckle" time to heal in its normal position.

我不得不在第一个月仰面而睡以便能够给“小扣带”时间让它恢复到正常的位置。

youdao

Normal face perception is just picking up on the melody of faces while people with prosopagnosia generally lack this ability (although to different degrees).

通常的脸部识别就像是在逐步熟悉脸部旋律，而面容失忆症患者一般就缺少这种能力(尽管程度不同)。

youdao

Her overwhelmed mother pretends everything is normal, and the family refuses to face the problem.

VOA: standard.2010.07.22

The Y2K Cooperation Center warned that The Gambia's official computer systems could still face problems when normal work resumes after the new year holiday.

BBC: Gambia weathers Y2K risk

' They just want to have a normal face.

CNN: The story

The two men have yet to face off in anything resembling normal political circumstances, with no election furore or freakish mishaps.

ECONOMIST: Bagehot