The leg to be stretched should be positioned behind your trunk with your knee bent.
要伸展的那条腿应该放在躯干的后面并弯曲膝盖。
《柯林斯英汉双解大词典》
2
You might be in heavy traffic with another vehicle right behind you.
你可能身处滚滚车流中，而另一辆车正跟在你后面。
3
The marsupial's eye problem may be to do with her diet before she was abandoned, or because she is overweight, leading to fat deposits behind her eyes.