MODAL VERBS (ĐỘNG TỪ KHUYẾT THIẾU) ACTIVE (CHỦ ĐỘNG): Will Would may/might must Need Can S+ Could Should Be able to Ought to Had better Have to + V(nguyên thể) + O PASSIVE (BỊ ĐỘNG): Will Would may/might must Need Can S+ Could Should Be able to Ought to Had better Have to + BE + PII