maintain
单词辨析：
指经常维修机器、建筑物等，使其保持良好状态。
Which company is responsible for maintaining this equipment?
哪家公司负责维护这台设备？
The garden is large and difficult to maintain.
这个花园很大，难以养护。
较正式用词，通常指保护自然资源使其不发生改变或破坏。
We must conserve our land/natural resources for future generations.
我们必须为后代子孙保护土地/自然资源。
Some environmentalists urged that the government take effective measures to conserve the wildlife.
一些环保人士呼吁政府采取有效措施保护野生动物。
指将某物完好地保存，通常用被动语态。
The city council spent a lot of money to preserve the old castle.
市政委员会花了不少钱来保护那座古城堡。
This bowl has been preserved intact.
这个碗保存得完好无损。
The house from 15th century has been perfectly preserved.
这座建于15世纪的宅第保存完好。
含较强的主观意味，指坚决而明确地表示某事真实无误。
She asserted that French cooking is the best in the world.
她坚称法国菜是世界上最好的。
The scientist asserted that there is no water on the moon.
那位科学家断言月球上没有水。
指声称某事属实，含有与他人进行争辩的意思。
He contended that it was true.
他声称那是真的。
I would contend that unemployment is the most serious social problem today.
我认为失业是当今最为严重的社会弊病。
指坚决维护某种主张或观点等。
She maintained her innocence.
她坚持自己是无辜的。
He maintains that he once saw a UFO.
他坚称自己曾看见过飞碟。
相关例句：
He should pay and maintain you as well.
他得给你钱，还得供养你。
His critics maintain that he's responsible for many of Algeria's ills.
他的批评者们坚持认为他应该为阿尔及利亚所面临的许多难题负责任。
The situation in the capital forced them to maintain military preparedness.
首都的形势迫使他们时刻做好军事准备。
He was arguing with the King about the need to maintain the cavalry at full strength
他正和国王讨论保留骑兵全部力量的必要性。
He has the power to use force to maintain public order.
他掌握着动用武力维持公共治安的权力。
Only by keeping down costs will America maintain its competitive advantage over other countries
只有通过控制成本，美国才能保持对其他国家的竞争优势。