这些动词均含有“断言，声称”之意。
assert ：主观意味强，指自认为某事就是如此，而不管事实如何。
- Altman asserted, 'We were making a political statement about western civilisation and greed.'
奥尔特曼坚称，“我们那时正要发表一份关于西方文明和贪婪的政治宣言。”
affirm ：侧重在作出断言时表现出的坚定与不可动摇的态度。
- Both sides affirmed their commitment to the ceasefire.
双方均申明答应停火。 - I can affirm that no one will lose their job.
我可以肯定，谁都不会丢掉工作。
allege ：多指无真凭实据，不提供证据的断言或宣称。
- She alleged that there was rampant drug use among the male members of the group.
她声称该团体中有大量的男性成员吸毒。
maintain与assert近义，但前者指坚决维护某种主张或观点。
- He has maintained that the money was donated for international purposes.
他坚称这笔捐款将用于国际用途。
testify ：多指在法庭作证，庄严地宣称自己所说属实。
- Several eyewitnesses testified that they saw the officers hit Miller in the face.
几位目击证人证明他们看见那几个警官打了米勒的脸。
claim ：可与assert换用，但语气弱一些，侧重指行为自己的权利提出要求他人承认。
- He claims (that) he was not given a fair hearing.
他声称他未得到公正的申述机会。
