Jane these families of chimps for many years and helped people understand how much they behave like humans.
A. had studied
B. studied
C. studies
D. has studied
网友回答
A. had studied
B. studied
C. studies
(答案→)D. has studied
解析：考查时态。现在完成时表示过去所发生的事情对现在的影响，在本句中体现出来了。句意：Jane已经研究了猩猩家族很多年了，并帮助人们理解猩猩有很多方面都像人类一样。