“变形虫”造句

变形虫是很简单的生物体.
The amoeba is a very simple organism.

当环境不利时,变形虫产生包囊.
An amoeba forms a cyst when conditions are unfavourable.

变形虫, 一种淡水生物, 就是这种情况.
The amoeba, a denizen of fresh water, is such a case.