重要的是：上背和颈部要挺直以支撑头部，这一点很重要。

It is crucial that the upper back and neck are held in an erect position to give support for the head.

《柯林斯英汉双解大词典》

将你的肩胛挤到一起，专注于拉伸你的上背。

Squeeze your shoulder blades together and concentrate on stretching your upper back.

youdao

如果你的肩膀和上背还会向颈椎挤压，说明你需要做更多的练习来加固根基。

If your shoulders and upper back are collapsing into your neck, you need further practice to build your foundation.

youdao

So verse 4, "You've seen what I did to the Egyptians, how I bore you on eagles' wings," is the historical prologue.

诗4，“我在埃及人所行的事，我将像鹰一样，将你们背在翅膀上“，就像是历史开场白。

耶鲁公开课 - 旧约导论课程节选

It's not going to be a backscatter event if your ping-pong ball hits the frame or these strings, or the top part.

打到原子核了就是背散射,如果打到框上。

麻省理工公开课 - 化学原理课程节选

We know we need to divide by 266, 266 but what we need you to help us with is to figure out this top number here and see how many particles are going to backscatter. So if the TAs can come up and quickly hand out 1 particle to everyone.

知道背散射的概率就可以了，我们知道要除以,但还需要你们来搞清楚,分子上的数是多少，有多少个发生背散射的粒子,助教们请过来,把这些球分给同学们。

麻省理工公开课 - 化学原理课程节选