含蓄条件：without / but for / otherwise
条件不写成 if 从句，而由介词或副词暗示，主句照样要用虚拟语气。
Without / But for + 名词，主语 + would (have) done
要点
- without / but for（要不是）暗示与事实相反的条件：Without your help, I would have failed.
- 时间对照着选形式：与过去相反用 would have done，与现在相反用 would do。
- otherwise / or（否则）也能含蓄表达条件：He was ill; otherwise he would have come.
- 真实条件的 or 用一般将来时，不虚拟：Put on your coat, or you'll catch a cold.
- 改写回 if 从句是常考题型：Without water, living things would die. = If there were no water, living things would die.
- and 那一头也能含蓄给条件：One more step, and you would have fallen. —— 前面那块常说数量或时间（One more step ／ Half an hour more），后半句照样要虚拟。
- 主句那头的 could ／ might 一样要接 have done：Without the map, they might have been lost for a week. —— 漏了 have，说的就变成现在的事。
- otherwise 是副词，不是连词：两个分句之间要用分号或句号，只用一个逗号就把两句粘在一起 —— The car broke down; otherwise we would have arrived on time.
例句
But for the rain, we would have started earlier.
要不是下雨，我们早就出发了。
Without air, man would die.
没有空气，人就会死。
He didn't take my advice; otherwise he would not have failed.
他没听我的建议，否则不会失败。
I would have been hurt but for your help.
要不是你帮忙，我就受伤了。
Two more minutes, and they would have reached the top.
再多两分钟，他们就到顶了。
But for the thick fog, we could have landed yesterday.
要不是那场大雾，我们昨天就能降落了。
易错提示
- 看到 without / but for / otherwise，先定时间再定时态：说过去的事用 would have done，说现在用 would do。
- but for 与 without 在这个意义上可互换，但 but for 更书面，多用于「要不是某个人/某件事」。
- but for 后面只挂名词或代词，接不了句子；要说"要不是他来了"就得回 if it were not for… 那一式（见「虚拟语气：条件句」）。