They want to get as far away from each other possible, the ideal angle is 120. But what we have here is a four-membered ring, so what angle does 90° that have to be, that bond? 90 degrees.

它们想要尽量远离彼此，最理想的是形成120°键角,但现在是个四元环,所以这键角应该多大？

麻省理工公开课 - 化学原理课程节选

And just to give you a sense, if you do a cross-cut of this, you cannot show it from this angle, but it should really be sort of a dumbbell shape with the nodal plane in between the two nuclei.

告诉你们这些就是给你们点概念，假如你们把他横切切开，不能从角度上展示，但它还是会保留几分哑铃的形态,以及在两核之间的节面。

麻省理工公开课 - 固态化学导论课程节选

Another way to represent a point in a plane is I've got a radius and I've got an angle from the x-axis, right, and that's a standard thing you might do.

平面上面的点的方法,也就是极坐标,上面那种方法其实是，如果你们喜欢我这么说的话,笛卡尔坐标表示法。

麻省理工公开课 - 计算机科学及编程导论课程节选

Now take these two fingers-- the middle finger and the thumb-- and as much as possible, from that 90 degree angle, create a circle.

再让这两个手指-,中指和姆指-,尽可能保持直角时围成一个圆圈。

哈佛公开课 - 幸福课课程节选