As winter temperatures drop to minus 10 degrees Celsius, their dense fur keeps them warm.
冬天气温降至-10°C，他们浓密的毛发起到了保暖的作用。
Mutual grooming not only keeps their precious fur in good condition, but also helps to reinforce bonds within the troop.
互相修理毛发不仅有助于保持宝贵毛发的良好状态，同时有助于增进成员间的关系。

重点讲解：

1. not only...but (also)...

不仅……而且……；

eg. We should not only be bold, but also be cautious.

我们不仅要大胆，而且要谨慎。

eg. His remark not only broke the ice, but aroused everyone's interest.

他的发言不仅打破了冷场，而且引起了大家的兴趣。

2. in good condition

情况良好； 完好；

eg. The salesman said the car was in good condition, and I was foolish enough to fall for it.

推销员说这辆汽车状况良好，而我那么傻竟然信以为真。

eg. He was obviously in good condition.

他的身体显然很健康。