1.
To descend by means of a parachute.
跳伞，伞降用降落伞下降
2.
drawdown [groundwater]
水位下降〔地下水〕
3.
descent:The act or an instance of descending.
"下降,降落:下降的动作或实例."
4.
A downward movement.
下降，落下向下的运动
5.
The temperature is going down; The barometer is falling; Real estate prices are coming down.
温度正在下降；气压下降了；房地产价格正在下降。
6.
compared with the figure in 1992, it has been decreased by 55%, among which the number in the urban areas has been decreased by 74% and in the rural areas the number has been decreased by 51%.
比1992年下降55%，其中城市下降74%，农村下降51%；
7.
A falling inflection of the voice, as at the end of a sentence.
声音降落，降句调发音时下降的音调
8.
lagging edge
【电】(脉冲的)下降边
9.
The birth rate have fall to twelve per hundred.
出生率下降到12％。
10.
The earthworm population had declined by 70%.
蚯蚓数量下降70％。
11.
A downward tendency, as in the price of a stock.
下降趋势如股票价格等的下降趋势
12.
A descent by stages or steps.
递减，下降一种逐级或逐步的递减，下降
13.
The Modified Steepest Descent Method──Best Point in Steepest Descent method
改进的最速下降法─最好点最速下降法
14.
a lowering of temperature below the freezing point
下降到冰点以下的温度
15.
The temperature fell to 26°below zero.
温度下降到零下26度。
16.
a vertiginous drop, descent, etc
令人眩晕的下落、 下降等.
17.
Of or relating to psychological depression.
（生理功能）衰弱的，下降的生理下降的，与生理下降有关的
18.
But when the temperature drops, so does the humidity level.
但是气温下降时，湿度也随之降低。