Each time it tries to pull its legs free, it sinks even further.

它每次尝试把腿拔出来都会陷得更深。

So to pull someone's leg means to fool or trick them but in a fun way.

to pull someone's leg的意思是指用一种有趣的方式愚弄或哄骗他人。

I tried to pull my leg away, but I just couldn't.

我试图把腿抽开，但就是做不到。

The quicksand will actually keep you afloat, and you'll be able to pull your legs free.

流沙实际上会让你漂浮起来，你就能把腿挣脱出来。

" And to-night he's coming to pull my leg, I suppose! I'm talking nonsense. The best thing I can do is to go to bed" .

“我想今晚他会来拉我的腿！我在胡说八道。我能做的最好的事情就是上床睡觉” 。