engage in参加; 从事; 忙于
例句：He engaged in a serious study of the problem.
他对这个问题进行了认真的研究。
associate with与…交往, 联系
例句：Foreigners always associate China with the Great Wall.
外国人总是把中国和长城联系在一起。
2. So, based on this association between greater cognitive activity and less amyloid, we think that these people will go on to have a reduced risk of Alzheiemer's Disease.
base on使建立在…基础上,立足
例句：Action should be based on solid facts.
行动应有确凿的事实为依据。
go on继续下去
例句：If he goes on like this he'll lose his job.
如果他继续这样下去,他会丢掉差事的。
3. Keep in mind that the people in this study, many of them in their 70s and 80s, did not show any symptoms of Alzheimer's.
keep in mind记住
例句：I'll keep your advice in mind.
我要把你的劝告记在心里。
4. And even if your brain hasn't been particularly active up until now, Landau says it's not too late to start ratcheting up your mental activities.
ratchet up逐渐升高，提升
例句：There 's nothing like a major holiday , such as Christmas , ratchet up the pressure on your schedule .
没有什么事情能够像重大的假日如圣诞节加大你日程计划表的压力。
