英语语法分析

I am not even certain what is meant by placental fluid.

我甚至不确定“胎液”到底指的是什么。

Is it human placental fluid, or, as some claim, horse's placental fluid?

这种胎液是人的，还是像其它传闻所说，是马的胎液？

If the cells did cross the placental barrier, the child's immune system should have recognised them as foreign invaders and destroyed them.

如果癌细胞确实穿过胎盘屏障，孩子的免疫系统应该会将它们视为入侵者，从而消灭它们。