江苏省高三英语情态动词 牛津版.docVIP

情 态 动 词 1.表示能力时，只能用can (现在) could do (过去能做) was/were able to do ： 过去能做 ( 2 ) 过去设法成功完成某一具体动作 =manage to do =succeed in doing Eg. 1.A blind man can not judge colors. 2.He could/was able to swim like a fish when he was young. 3.Though he was tired , he was able to swim across the river. 4.Because he was tired, he couldn’t /wasn’t able to swim across the river.(在否定结构中无区别) 2.表推测时：may/might( 语气最不肯定，多用于肯，否定句) 可能 can （语气肯定，一般不用于肯定句）可能 could (较can不确定，也可用于肯定句) 可能 must (语气最肯定，只用肯定句)一定 should(表可能性，推论，推测，期待等)按理该；估计 ought to (表可能性，揣测，猜测，期望等)照说应该，理应 may/might have +ed (语气不肯定) 过去可能…… can’t/couldn’t have +ed (语气肯定)过去不可能…… must have +ed (语气肯定) 过去一定 should have +ed 过去按理应该 ought to have +ed　　过去按理 Eg. 1.A: Look, someone is coming. Who can it be? B: It may be the headmaster. A:It can not be him.He has gone to Shanghai. B: It must be Mr Zhang. He looks like the headmaster. 2.I don’t know his age. He could be thirty or thirty-five. 3. The report is written after careful investigation, so it should be reliable. 4.---I didn’t see Mary at the meeting yesterday. ---She might have been ill, I guess. 5.The street are all dry. It couldn’t have rained during the night. 3. 表责备时： may/might have +ed（语气委婉）过去本可能… can/could have +ed (语气委婉) 过去本能…… should have +ed (语气强烈) 过去本应该……，而未…… ought to have +ed (语气强烈) 过去本应该……，而未…… needn’t have +ed 过去本不必…，却做了… Eg. 1.He might have given you more help, even though he was very busy. 2.---Did you listen to the speech? ----No, we could have attended it.But we had a lot of traffic on our way. 3.The plant is dead. Maybe I should have given more water. 4.Your brother’s failed in English again. You ought to have given him more help. 5. ---Mr Smith didn’t come last night, did he? ---- No. We needn’t have waited for him. A whole n