drift：trend, movement—a general tendency to change, as of opinion主要指思想方面的变化趋势
not openly liberal but that is the drift of the book并不是公开的自由，但却是该书的思想趋势
current: a tendency or course of events that is usually the result of an interplay of forces 主要指各方面相互作用之下产生的某种结果的趋势
currents of public opinion民意的趋势
tide: something that fluctuates like the tides of the sea根据tide“潮汐，浪潮”这一意思也能知道tide指的这种趋势应该是一时的大起大落的趋势
the tide of history 历史的潮流
The tide turns.形势转变, 局面改观。
trend: a prevailing tendency or inclination指一般的趋势
