Jane warns us that our group is going to be very tired and dirty by the afternoon and she is right. However, the evening makes it all worthwhile⑨. We watch the mother chimp and her babies play in the tree⑩. Then we see them go to sleep together in their nest⑪ for the night. We realize that the bond⑫ between members of a chimp family is as strong as in a human family.

　　①student在此不作"学生"讲，而是"研究者""学者"的意思。

　　②现在分词短语following Jane's way of studying chimps作方式状语。

　　③behave/bI'heIv/vt.&vi.举动；(举止或行为)表现

　　behave oneself/well守规矩/举止得体

　　behaviour/bI'heIvjə/n.(＝behavior)行为；举止；习性

　　④动名词短语watching a family ...作主语，谓语动词用单数形式。

　　⑤mean doing sth.意味着做某事

　　mean to do sth.打算做某事

　　⑥where引导的定语从句修饰the place。在定语从句中现在分词短语sleeping in a tree作后置定语。

　　⑦in the shade of ...在......的阴凉处

　　shade/ʃeId/n.荫；阴凉处 vt.遮住光线

　　⑧move off离开；起程；出发

　　⑨worthwhile/wɜːθ'waIl/adj.值得的；值得做的

　　It is worthwhile to do sth./doing sth.做某事是值得的。

⑩句中用了"感官动词＋宾语＋宾补"结构，且and后省略了感官动词watch。