速度的符号已经，由负变正了，可是加速度又还是正的。

It has changed from a minus sign to a plus sign because of this positive acceleration.

youdao

第一位是符号位，0表示正，1表示负。

The first bit is the sign bit, 0 for positive and 1 for negative.

youdao

因此我决定，在此处改变正方向，加速度方向就始终为正了，符号变了。

So the moment that I decide to define this the plus direction will also come out to be the same sign as this one so I flip the signs there.

youdao

dS/dV And that, now, we know must equal dS/dV, with a positive sign. At constant temperature.

我们知道这个等于恒定温度下的，符号为正。

麻省理工公开课 - 热力学与动力学课程节选

Delta v is positive in this direction here, the work is negative. So work on the system is positive. Work done by the system is negative.

功是负的，总而言之,外界对系统做功的符号为正。

麻省理工公开课 - 热力学与动力学课程节选

sa So we have 1 s a, and we're drawing this as having a positive amplitude, but since we have destructive interference we're going to draw 1 s b as having the opposite sign, so we have a plus and a minus in terms of signs.

我们有，我们把这画成一个正的振幅，但因为我们是相消干涉,我们把1sb画成相反的符号，所以我们有一正一负两个符号。

麻省理工公开课 - 化学原理课程节选