(1) ①reduce表示“(以人为的因素)使(体积、大小、数目、程度、价格、速度、成本、开支、压力等)变小、降低”，常可与lower换用。
- You'll have to reduce your article to half the number of the words.
你得把你的文章压缩到现有字数的一半。 - If the pressure is not reduced, the cylinder is likely to fracture.
如果压力不减小的话，这个气缸就有可能会爆裂。 - Some TV factories scramble to reduce/lower their prices.
一些电视机厂家竞相降价。
②reduce作不及物动词，表示“设法减轻体重，减肥”。
- Oh, no sugar, please, I'm trying to reduce .
哦，请不要放糖，我在试图减肥。 - You'll have to reduce to get into that dress.
要想穿上那件衣服，你得减肥。
③reduce to可表示：
A . 使陷入(某种不良境地)。
- During the famine, many people were reduced to eating grass and leaves.
那次饥荒中，许多人陷入以吃草和树叶为生的境地。 - The great fire reduced the grand building to a mere ruin.
那场大火使这座宏伟的建筑沦为一片废墟。
B． 把……研磨/分解成……
- Water can be reduced to oxygen and hydrogen by electrolysis.
水通过电解可分解成氢和氧。
C． 折算成(小单位)。
- You can reduce the amount in pounds to new penny by quite simply multiplying by 100.
你通过很简单地用100相乘，就可以把镑折算成新便士。
D． 使身体变到(某一不良情况)。
- Many Iraqi children have been reduced to skin and bones because of lack of food and medicine brought about by U.N. sanction.
由于联合国的制裁所造成的食品和医药短缺，许多伊拉克儿童瘦得皮包骨头。
(2) ①decrease意为“缩短，变小，减少”。
- Your hunger decreases as you eat.
当你吃东西时，你的饥饿感会随之减轻。 - The population of the city has decreased by 5,000 to 150,000 as a result of the war.
由于这场战争，这座城市的人口减少了5 000人，还剩15万人。
②decrease有时作“(使)减轻，消减”解。
- These pills can ease pain and decrease swelling.
这些药丸可以去痛消肿。 - I shall have to decrease your wages if you are late for work again.
如果你再上班迟到，我将不得不削减你的薪水。 - Do decrease the dose of medicine, as you feel better.
当你感到好些时，一定要减少服药的剂量。
(3) diminish意为“(使)减少，缩小，变弱，降低，贬低”，常可与decrease换用。
- The unwise/unpopular decision diminished his popularity.
他的不明智的/不得人心的决定降低了他的威信。 - His constant attempts to diminish the achievements of others eventually led to his dismissal/downfall.
他不断地试图贬低别人的成就最终导致他被解雇/垮台。 - The three-year-long war seriously diminished/decreased the country's wealth.
拖了三年之久的战争大大减少了这个国家的财富。
(4) ①dwindle意为“(逐渐)变小、变少”，只用作不及物动词，可与decrease, diminish(用作不及物动词时)换用。
- The number of students is dwindling/decreasing in that school.
那所学校的学生人数在逐渐减少。 - Our food supply dwindled/decreased/diminished when we were lost in the woods.
我们在树林中迷路时，我们的食物供给逐渐减少。
②dwindle用于健康，表示“变坏，变差”。
- His health dwindled slowly year by year.
他的健康慢慢地在逐年变坏。
(5) ①lower指“使(价格、价值、标准、位置等)降低，降下，减少”，多作及物动词。
- You'll have to lower your prices if you want to find a market for your products.
你如要为你的产品找到市场你就得降低价格。 - Poor diet lowers resistance to illness.
劣质饮食会降低人体对疾病的抵抗力。 - The horse lowered its head to drink from the river.
那匹马低下头去喝河水。
②其他还可以说：lower expenses/one's voice to a whisper/cost/prestige/pressure/a flag...
③有时也可用作不及物动词。
- The stocks lowered in value.
这些股票贬值了。 - The moon is lowering in the west.
月亮西沉。
④lower oneself是“失身份，降格(做某事)”。
- He would never lower himself to take bribes (by taking bribes).
他绝不会降低身份接受贿赂。 - I hope you will not lower yourself to such bad behavior.
我希望你不会降格去做出那种坏事。
(6) wane除表示“(月亮)逐渐变小，(月)亏”外，也表示“(力量、健康、影响、声望等的)下降，减弱”，是较书面的说法。
- The moon wanes after it has become full.
月亮圆了之后又逐渐变小。 - His influence/reputation is waning .
他的影响/声望在下降。 - The old man's health is waning day by day.
这位老人的身体在一天天衰弱下来。
