题目

阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。Monkeys do not like it when others get more food 【1】 they do, according to a new study.Researchers from Yale and Harvard universities found Capuchin monkeys punish monkeys 【2】 get more food. This sort of, 'If I can't have it, no one can' response is because 【3】 psychological spite (怨恨), and it was【4】 (previous) thought unique to humans, said Kristin Leimgruber of Harvard University. She is a co-author of the research study. The researchers watched as some Capuchin monkeys 【5】 (食物链中开始的生物通常是（ 　） A．食草的　B．进行光合作用的   C．食肉的　　D．腐生的