free flagellum

例句：

1. 1. The bacteria are able to move through the water by using their free flagella.
   这些细菌能够通过使用它们的自由鞭毛在水中移动。
2. 2. The spermatozoa swim in the egg's vitelline membrane, which is like a free flagellum.
   精子在卵子的透明带中游动，这就像自由鞭毛一样。
3. 3. The flagellum of the bacterium is a long, whip-like structure that helps it move through the water.
   细菌的自由鞭毛是一种长而鞭状的结构，帮助它在水中移动。