if-clauses (types 0–3)
规则if 从句设定条件,主句陈述结果。动词形式显示条件的现实程度。
好奇
「If it rains, I will stay」与「If it rained, I would stay」只差一个时态,意义却变了。怎么变?
直觉
条件句是现实度旋钮。现实/可能 → 现在 + will(第一类);此刻非现实 → 过去 + would(第二类);过去不可能 → had + 过去分词 + would have(第三类)。
可视化
看成分:条件(if 从句)与结果(主句)各自标注动词形式。关系是「条件 → 结果(第一类)」。
动词形式显示条件的现实度(此处为第一类)。
If the order arrives todaywe will ship it
本质
第零类(普遍真理):if + 现在, 现在。第一类(现实未来):if + 现在, will + 动词。第二类(现在非现实):if + 过去, would + 动词。第三类(过去非现实):if + had + 过去分词, would have + 过去分词。if 从句内不放 will。
例句
If you confirm by noon, we will deliver tomorrow.
若您中午前确认,我们明天发货。
If I were the manager, I would change the schedule.
如果我是经理,我会更改日程。
If we had ordered earlier, we would have saved money.
如果我们早点订购,本可以省钱。
小测验
「If the client ___ tomorrow, we will sign the deal.」填哪个?