上升和下降趋势的组合描述（嵌入了时间和程度之后）：
1. 先上升后下降的句型：
...... increased slowly during…… and …… but fell sharply in …….
A steady fall in …… during …… and …… followed the sharp increase in …….
2. 先下降后上升的句型：
…… fell before …… began to make a recovery ……
…… continue the recovery, climbing to ……
…… dropped during …… but increased again in ……
…… fell and then pick up during ……
…… collapsed before rising to ……at the end of ……
3. 起伏波动的句型：
…… fluctuated sharply all through ……
4. 波动不大的句型：
…… hardly changed through the period between ……and ……
柱状图形的描述
转换为线形图形的描述
