Modal verbs ในอดีต

Looking back with modals

• Past modals = modal verb + have + past participle
• ทำให้คุณเดา, สัมผัสถึงความเสียใจ, หรือจินตนาการเกี่ยวกับ past
• He must have left. I should have called.

He must have forgotten the appointment; his calendar looked equally surprised.

must have / can't have (deduction)

• must have + p.p. = คุณมั่นใจว่ามัน was จริง: He must have forgotten.
• can't have + p.p. = คุณมั่นใจว่ามัน wasn't: She can't have seen us.
• นี่คือการเดาอย่างมั่นใจเกี่ยวกับอดีต

should have (regret, criticism)

• should have + p.p. = "สิ่งที่ควรทำ, แต่มันไม่ได้เกิดขึ้น"
• I should have studied harder. (regret)
• You shouldn't have said that. (criticism)

could have / might have (possibility)

• could / might have + p.p. = มัน possible, แต่เราไม่แน่ใจ
• They might have missed the train. It could have been worse.
• could have ยังหมายถึง "能做, แต่ไม่ได้做"

ข้อผิดพลาดทั่วไป

• ❌ He must forgot. → ✓ He must have forgotten. — past deduction = modal + have + participle
• ❌ should of gone → ✓ should have gone. — of คือการได้ยินผิดของ have
• ❌ I could help you yesterday, but I was busy. → ✓ I could have helped you. — โอกาสในอดีตที่ไม่ได้ใช้