从句逻辑流 · 虚拟语气

核心识别特征：选项含情态动词 (should/would) 或 be动词原形
▶ 第一类：必须用 (should) do / be done 的情况

(注意：其中的 should 可以省略，直接填动词原形)

1 坚 2 命
3 建 4 要
▪ 1个坚持: insist
▪ 2个命令: order, command
▪ 3个建议: advice, suggest, propose
▪ 4个要求: ask, require, request, demand
* 包含这些词的名词/形容词形式 (如 requirement, suggestion) 后接的句子也适用。
句型与连词
▪ It is + adj + that (adj包括: important, vital, necessary, essential, strange, natural, advisable)
▪ 连词：in case, lest, for fear that (以防万一)
▶ 第二类：If 条件句推导公式
时间点 从句结构 (If部分) 主句结构
现 反 Ved / were would/could/should/might + V原
过 反 had done would/could/should/might + have done
将 反 Ved / should + V原 / were to + V原 would/could/should/might + V原

⚡ 进阶解题技巧

  • 判断时间：有时间状语看时状；无时状看动词(动词是Ved即过反，动词是V/Vs即现反)。
  • 错综虚拟：主从句时间不一致时，动词变化“各归各”，按对应时间各自变化。
  • If 省略倒装：省略 if 时，必须将从句的 should / had / were 提前到句首。
▶ 第三类：含蓄虚拟 (特殊词死记)
wish / if only
as if / though
对现在：Ved / were
对过去：had done
对将来：would do
would rather
(宁愿)
对现在/将来：Ved / were
对过去：had done
(等同于 would just as soon)
without / or
but for
对现在/将来：would do
对过去：would have done
It is time
It is (high/about) time + 句子 ➔ 必须填 should do 或 Ved (此处的should绝不能省！)

🎯 情态动词 + have done (对过去的推测)