关于英语问题while it is ture that the olfactory powers of humans a

关于英语问题
while it is ture that the olfactory powers of humans are nothing like as fine as those possessed by certain animals, they are still remarkably acute.前面的那those possessed by certain animals 什么意思. 为什么后面they are still remarkably acute.是一个完整的句子啊?难道while 引导是从句吗?