初二物理单元：压强练习试题

　　这篇关于初二英语下册第六单元知识点，是

　　被动语态：主语（动作承受者）←谓语（be+动词过去分词）←宾语（动作发出者）He wrote the letter. →The letter was written by him.4）主动句变被动句的基本句式：a) 主：主语+助动词（情态动词）+谓语+宾语被：主语（原宾语）+助动词（情态动词）+be+动词过去分词+by+原主语如，We will help him.→He will be helped by us.主：主语+动词短语+宾语被：主语（圆宾语）+be+动词短语的过去分词+by+原主语如，They looked after the babies.→The babies were looked after by them.主：主语+谓语+间接宾语+直接宾语被：主语（间接宾语）+be+动词过去分词+原直接宾语主语（直接宾语））+be+动词过去分词+to(for)+原间接宾语+（by+原主语）如，We gave him some magazines.→He was given some magazines.Some magazines were given to him by us.【注意】一般将主动句中表示人的间接宾语变为被动句中的主语。主：主语+谓语+宾语+宾语补足语被：主语（原宾语）+be+过去分词+原宾语补足语如，They elected him their monitor.→He was elected their monitor.【注意】如果主动句中宾语补足语是不带to的不定式，变成被动语态后一般要加to.I saw him go to the church.→He was seen to go to the church.【扩展】一般在以下几种情形时，需要使用被动语态。不知道动作的执行者，只知道动作的承受者时。When we got there, the room had been cleaned already.不必要说出或出于礼貌不便说出动作的执行者时。I was told that you were not honest enough.３）有必要突出或强调动作的承受者时。You were asked to answer this question.16.if与whether:if和whether均可用于宾语从句中，意为“是否”；if用于条件句中，表示“如果”，不能和or连用；whether常与or连用，表示两种条件或情况。【扩展】if not..如果不是…,表示惊讶或憎恶等情绪；if only意为“若…那就好了，我多么希望…”相当于how I wish；only..if..意为“决不…除非…”If it hadn’t been for the doctor’s care, I should not be speaking to you now.如果不是医生的照顾，我现在就不会和你说话了。If only he arrives in time!若他及时到达就好了。I’ll only come if you promise me that you won’t invite Henry.除非你答应不请亨利，否则我不会来。