有三个类似题目都做错了，哪位好心人能帮帮忙

 1。a researcher discovered that people whio have law level of immune system activity tend to score much lower on the test of mental health than do people with normal and high immune system activity. the researcher concluded from his experiment that the immune system portects against mental illness as well as against physical diease.

2. a study of material relationship in which one partner's sleeping and working cycles differ from those of the other partner reveals that such couples shear fewer activities with each other and have more violent arguments than do couples in a relationship in which both partners follow the same sleeping and working pattens. thus, mismatched sleeping and working cycles can seriously jeopardize a marriage.

3. a reaearcher studying drug addits found that on average, they tend to manipulate other people a great deal more than nonaddicts do. the researcher canclude that people who frequently manipulate other people are likely to become addicts.

这三个我感觉都是类似的情况， 做完第一和第二个我就已经总结他们是一样的了，但是碰到第三个还是错了。  现在想把他们的逻辑结构推理一下但是越想越感觉晕。最后就感觉没有关联了。 哪位高手能够指点一下迷津， 他们的逻辑结构，遇到这种类型怎么下手？

谢谢了。