Alter和change:
Alter和change用做不及物动词时，意义极相似，都表示“改变”，常可通用，一般情况下，用change更好，如：His appearance has changed/altered a great deal.
做及物动词用时，change往往表本质、彻底地或以新代旧的改变，而alter常意味局部的、表面的改变：
This coat is too big. I must have it changed.（改）
This coat is too big. I had better change it. （换）
One may alter a coat without changing its style.
Movement和campaign:
Movement和campaign都可当“运动”讲，movement多指历史上重要的运动，如the May Fourth Movement, the Enlightenment Movement等比较长期、范围较广、影响较大的政治、社会或文化运动。
Campaign的本义是“战役”，引申为轰轰烈烈的“积极宣传”或有战斗性的运动，其目的比movement明确单纯，时期较短、轰动性较大，如：election campaign, the patriotic public health campaign, the 5-good family campaign.
Obligation和duty
Obligation和duty都有“义务”、“职责”、“责任”的意思，但obligation往往表示“特指的、带有约束力的、强制的义务”，如：
He is under the obligation of supporting his aged mother.
Every citizen has the obligation to perform military service.
The place is not only for worship but also for the fulfillment of many other social obligations, civic, educational, and recreative.
而duty多指“道义上的责任”、“本分”，比较强调自觉性，如：
Public assessment of an individual also includes one''s obligation towards one''s parents, and there is strong social condemnation of those who neglect this duty.
to be torn between duty and self-interest.
