[单选题]湿式空气滤清器是在其底部装有一定数量的（?? ），利用粘性作用、吸附空气中的灰尘杂质使空气净化。
A.水
B.黄油
C.润滑油
D.柴油

A. As the researchers hypothesized, participants who were feeling blue were more likely to respond to and express a preference for familiar patterns, whereas more cheerful participants displayed no preference for familiar over previously unseen patterns. That is, happy participants still appreciated the familiar--in some instances, even more passionately than those in a bad mood--but their mood also boosted positive reactions to new things. As the authors put it, if desire for the familiar can be expressed as a "warm glow of familiarity," then perhaps good mood casts a similar ray of sunshine on the new, creating a "warm glow of novelty."
B. Other theorists have suggested that the value of familiarity is more relative and contextual. That is, a familiar face is more appearing in situations of danger or disorientation--running into a hometown neighbor while wandering around an unknown city might evoke a "warm glow," while bumping into that sam