In this sentence

①complaints (about / against sth/sb)n.抱怨；牢骚

Synonymsgrievances, grumbles, protests

在本句中，complaints 用作可数名词复数，表示“抱怨、发牢骚”，与前文的 solution（解决方案）形成对比，意指纯粹的情绪发泄或不满，而无法解决实际问题。

• Never make excuses, and never make complaints.永远不要找借口，永远不要发牢骚。— Montague Burton

②make / lodge a complaint (about / against sth/sb)n.（正式的）投诉；控告

Synonymsallegations, objections, charges

• Those who have the courage to lodge a complaint against injustice are the architects of a fairer world.敢于对不公提出正式抗议的人，是构建更公正世界的缔造者。

③a medical / health complaintn.（微小的）疾病；身体不适

Synonymsailment, illness, disorder

• Listen to the mild complaints of your body today, lest they become the severe afflictions of tomorrow.今日且听身体的微恙，莫待明朝成沉疴。

In this sentence

①a proposal for sth / to do sthn.提议；方案

Synonymssuggestion, scheme, plan

在本句中，proposal 指代具体被验证的“计划方案”（与前半句的 proposed solution 相呼应，与抽象理论 theories 相对立）。

• Every proposal for reform contains within itself the seeds of a new abuse.每一项改革提案的内部，都包含着新弊端的种子。— Sydney Smith

②a marriage proposaln.求婚

Synonymsoffer of marriage

• A marriage proposal is the only question where a simple yes or no changes the entire course of two lives.求婚是唯一一个仅凭简单的是或否，就能彻底改变两个人一生轨迹的问题。

In this sentence

①a proposed sthadj.提议的；建议的；拟议的

Synonymssuggested, recommended, projected

本句中 proposed 作前置定语修饰名词 solution，表示“被提议出来的解决方案”或“拟议的方案”，与后半句的 tested（经过测试的）形成对照。

• Every proposed change brings fear, but progress is impossible without change.每一项拟议的变革都会带来恐惧，但没有变革就没有进步。

②propose sthv.提出；建议

Synonymsput forward, advance, submit

• Newton proposed that gravity is a universal force governing the motion of all things.牛顿提出，引力是一种支配万物运动的普遍法则。

③propose to sbv.向某人求婚

Synonymsask for sb's hand, pop the question

• He proposed to the woman he loved, knowing that true love begins where selfish demands end.他向所爱的女子求婚，因为他懂得，当自私的索求停止时，真爱方才始萌。

①protest against / about / at sthv.抗议；反对

Synonymsobject, oppose, demonstrate

• To sin by silence, when they should protest, makes cowards of men.在应当抗议时保持沉默而犯罪，会使人沦为懦夫。— Ella Wheeler Wilcox

②protest sth / that...v.坚决声明；申辩

Synonymsinsist, assert, maintain

• The lady doth protest too much, methinks.依我看来，这位女士表白得有些过分了。— William Shakespeare

③a protest against sthn.抗议活动；反对行动

Synonymsdemonstration, rally, objection

• Art is a protest against extinction.艺术是对消亡的一种抗议。— André Malraux

④in protest / without protestn.抗议中；抗议地 / 顺从地

Synonymsdefiance, dissent, complaint

• He who accepts evil without protest is really cooperating with it.不加抗议而接受邪恶的人，实际上是在与邪恶同流合污。— Martin Luther King Jr.