Trust is a tricky business. On the one hand, it’s a necessary condition (1)_____ many worthwhile things: child care, friendships, etc. On the other hand, putting your (2)_____ in the wrong place often carries a high (3)_____.

    (4)_____, why do we trust at all? Well, because it feels good. (5)_____ people place their trust in an individual or an institution, their brains release oxytocin, a hormone that (6)_____ pleasurable feelings and triggers the herding instinct that prompts humans to (7)_____ with one another. Scientists have found that exposure (8)_____ this hormone puts us in a trusting (9)_____ : In a Swiss study, researchers sprayed oxytocin into the noses of half the subjects; those subjects were ready to lend significantly higher amounts of money to strangers than were their (10)_____ who inhaled something else.

    (11)_____ for us, we also have a sixth sense for dishonesty that may (12)_____ us. A Canadian study found that children as young as 14 months can differentiate (13)_____ a credible person and a dishonest one. Sixty toddlers were each (14)_____ to an adult tester holding a plastic container. The tester would ask, “What’s in here?” before looking into the container, smiling, and exclaiming, “Wow!” Each subject was then invited to look (15)_____. Half of them found a toy; the other half (16)_____ the container was empty and realized the tester had (17)_____ them.

    Among the children who had not been tricked, the majority were (18)_____ to cooperate with the tester in learning a new skill, demonstrating that they trusted his leadership. (19)_____, only five of the 30 children paired with the (20)“ _____ ” tester participated in a follow-up activity.

答案精析：此空所在句子是同位语从句，补充说明催产素（oxytocin）是什么物质。此空后面出现and triggers，说明此空的单词和triggers是并列关系，都在对催产素做解释，应填入含有“激发，引发”意义的单词，produces符合题意。此句意为：催产素是一种荷尔蒙，它能产生愉快情绪，激发人类的群聚本能。

错项排除：荷尔蒙无法对情绪进行选择或应用，A和C错。D选项是一个强干扰项，maintains侧重于维持原本存在的事物或继续原本进行的某事，且与triggers无法在语义上构成并列关系，故错误。