在一系列的时间段中转变：changes over time
持续变化的data在不同情况下：
增加：increase/raise/rise/go up ...
减少：decrease/grow down/drop/fall ...
波动：fluctuate/rebound/undulate/wave ...
稳定：remain stable/stabilize/level off ...
最常用的两种表达法：
动词 + 副词形式(Verb + Adverb form)
形容词 + 名词形式(Adjective + Noun form)
1. Verb + Adverb form
The number of XXX
+increase/jump/rise/decrease/drop/fall/fluctuate...
+insignificantly/significantly/slightly/suddenly/rapidly/dramatically/sharply/steeply/steadily/gradually/slowly...
+from (第一时间) to (第二时间)/between (第一时间) and (第二时间)
2. Adjective + Noun form
There was + a
sudden/rapid/dramatic/significant/sharp/steep/steady/gradual/slow/slight
+increase/jump/rise/decrease/drop/fall/fluctuation
(注意：上述很多词不可用于修饰fluctuation)
+in the number of XXX from (第一时间) to (第二时间)/between (第一时间) and (第二时间)
