摘要: A if从句中的动词用过去完成时,主句中的动词用条件完成时。这种句子所指的时间是过去;所提出的条件是不可能实现的,因为if从句中的动作在过去并未发生:If I had known that you were coming I would have met you[阅读全文:]
摘要: A if从句中的动词用一般过去时,主句中的动词用条件时态:If I had a map I would lend it to you.我要有地图就借给你。(但我没有地图。句子的含义是指现在。)If someone tried to blackmail me I would tell the[阅读全文:]
摘要: A if从句中的动词是一般现在时,主句的动词是一般将来时,主句和从句的先后次序无关紧要:If he runs he’ll get there in time.如果他跑步去就会及时赶到那里。The cat will scratch you if you pull her tail.如果[阅读全文:]
摘要: A 这种时态由would/should+完成式构成:肯定式: I would/should have worked  [阅读全文:]
摘要: A 条件现在时由would/should+动词原形构成(用于第一人称),或由would+动词原形构成(用于其他人称):肯定式: I would/I’d work/I should work [阅读全文:]
摘要: A 助动词do用来构成普通动词现在式和过去式的否定式和疑问式: He doesn’t work. 他不工作。 He didn’t work. 他以前不工作。 Does he work? 他工作吗? Did he work? 他以前工作吗? B 想特别加重语[阅读全文:]
摘要: A have的基本含义是“拥有”: He has a black beard. 他长着黑胡子。 I have had this car for ten years. 这辆车我已经买了十年了。 She will have£4,000 a year when she retires. 她退休后,每年将得[阅读全文:]
摘要: A be通常用来表示人或物的存在 Tom is a carpenter. 汤姆是木匠。 The dog is in the garden. 那只狗在花园里。 Malta is an island. 马耳他是一个岛国。 The roads were rough and narrow.道路既崎岖又狭[阅读全文:]