它们的质量非常接近零，因此，即使在中等能量下，我们也希望它们以光速传播。

They are very nearly massless and thus, even at moderate energies, we'd expect them to travel essentially at the speed of light.

youdao

然后以中等强度跑800米(比10000米比赛的速度要慢)，做2到8个跨栏跑。

Then run 800 meters at moderate intensity (a little slower than your 10-k race pace), and do two to four 100-meter strides.

youdao

而肥胖在美国各社会经济阶层的发生率并不平均，以中等和中等以下收入群体为最多。

Obesity does not occur evenly across all socio-economic strata in the U.S.; it is far more prevalent in middle to lower income groups.

youdao