1. 使持续;保持
    If you sustain something, you continue it or maintain it for a period of time.

    e.g. But he has sustained his fierce social conscience from young adulthood through old age...
           而他从青年时期一直到老年都始终保持着强烈的社会良知。
    e.g. The parameters within which life can be sustained on Earth are extraordinarily narrow.
           地球上生命可以存活下来的地域范围是非常狭小的。

2. 经受;遭受;蒙受
    If you sustain something such as a defeat, loss, or injury, it happens to you.

    e.g. Every aircraft in there has sustained some damage...
           那里的每架飞机都受到了一些损坏。
    e.g. A seventeen-year-old tourist died late last night of injuries sustained in yesterday's bomb blast.
           一位 17 岁的游客在昨天的炸弹爆炸中受伤并于当天深夜身亡。

3. 支持;支援;救济
    If something sustains you, it supports you by giving you help, strength, or encouragement.

sustain什么意思

    e.g. The cash dividends they get from the cash crop would sustain them during the lean season...
           从经济作物中获得的收益能帮助他们度过不景气的时期。
    e.g. I am sustained by letters of support and what people say to me in ordinary daily life...
           这些支持的信件和人们每天对我的鼓励一直支撑着我。