科技英语6 虚拟语气ppt课件.ppt
,第六章 虚拟语气,6 .1 三种语气简介,1、陈述语气 。,2、祈使语气：注意三种否定形式。,Dont be fooled（受愚弄）；some very simple circuits can be quite useful.,In this case, let us not apply KCL（基氏电流定律）at this node（节点）.,Dont you dare to do that!,6 .1 三种语气简介,3、虚拟语气,（1）与事实相反的情况；不可能或难以实现的情况。,（2）表示主观愿望、要求、建议等。,（3）表示客气和语气委婉。,6 .2 科技英语中虚拟语气的主要形式,1、条件式,先做几个动词填空题：,_ (be) there no resistance of the air, all bodies at the same height would fall at the same speed.,The instrument _ (not damage) had the voltage not been so high.,6 .2 科技英语中虚拟语气的主要形式,1、条件式,先做几个动词填空题：,_ anything abnormal（异常的）_ (happen), switch off the power supply at once.,6 .2 科技英语中虚拟语气的主要形式,1、条件式,涉及现在、将来：,从句,主句,过去时 (be were),过去将来时,shouldwouldcouldmight,+ 动词原形,6 .2 科技英语中虚拟语气的主要形式,1、条件式,涉及过去,从句,主句,过去完成时,过去将来完成时,shouldwouldcouldmight,+ have + 过去分词,6 .2 科技英语中虚拟语气的主要形式,1、条件式,涉及将来,从句,主句,（should +）动词原型,过去将来时,一般将来时,were + 不定式,6 .2 科技英语中虚拟语气的主要形式,1、条件式,He probably could have added the same three numbers with paper and pencil in much less time than it took him to write the program.,If the sign of inequality（不等式）be reversed, u has neither a maximum nor a minimum.,6 .2 科技英语中虚拟语气的主要形式,If the positive charge did move in a wire, it would move from the positive to the negative.,6 .2 科技英语中虚拟语气的主要形式,*注意：当“if ”省去后，从句要发生部分倒装（与一般疑问句类同）。,Should the bomber（轰炸机）encounter（遇到）such an air-defence system, the result would be fatal（致命的）.,6 .2 科技英语中虚拟语气的主要形式,The mornings newspapers predicted（预计）a dire（可怕的）disaster（灾难）that day should a widespread computer virus（病毒）detonate（起爆）its logic bomb.,*注意：当“if ”省去后，从句要发生部分倒装（与一般疑问句类同）。,6 .2 科技英语中虚拟语气的主要形式,2、在主语从句、宾语从句、表语从句、同位语从句中,这种虚拟语气与主句中的某些及物动词、形容词、名词有关。,虚拟形式：,(should +) 动词原形,常见的及物动词：,require, suggest, desire, propose, recommend, necessitate, request, demand, order, ,6 .2 科技英语中虚拟语气的主要形式,常见的形容词：,necessary, essential, imperative, important, possible, impossible, desirable, natural, reasonable, preferable, better, ,常见的名词：,requirement, suggestion, neces- sity, importance, recommenda- tion, request, philosophy, condi- tion, constraint, restric-tion, restraint, ,6 .2 科技英语中虚拟语气的主要形式,填动词练习：,It is of paramount（至高无上的）importance that correct measurements _(carry) out at every step.,It is evidently desirable that resistance of the instrument _(be) much smaller than that of the remainder（其余部分）of the circuit.,6 .2 科技英语中虚拟语气的主要形式,填动词练习：,Their suggestion is that the water level _(raise).,A necessary condition that this _(be) the case is that Eulers Equation（尤拉方程）_(satisfy).,6 .2 科技英语中虚拟语气的主要形式,填动词练习：,Long, long ago, a scientist suggested that the earth _(be) round（圆的）.,6 .2 科技英语中虚拟语气的主要形式,suggest:,“建议”要用虚拟语气,“认为；表明”要用陈述语气,insist:,“坚决要求”要用虚拟语气,“坚持认为主张”：要用陈述语气,6 .2 科技英语中虚拟语气的主要形式,3、在某些状语从句中,对现在的情况：,（1）“as if as though”,对过去的情况：,We have for simplicity been speaking of the current in a conductor as if all of the free electrons moved with the same constant velocity.,用过去时,用过去完成时,6 .2 科技英语中虚拟语气的主要形式,3、在某些状语从句中,（1）“as if as though”,At that time it looked as if the instrument had been damaged.,对现在的情况：,对过去的情况：,用过去时,用过去完成时,6 .2 科技英语中虚拟语气的主要形式,3、在某些状语从句中,（2）“whether or ”句中省去“whether”时一定采用 “be it they or ” 形式,Everything around us, be it air, water or wood, is matter.,6 .2 科技英语中虚拟语气的主要形式,3、在某些状语从句中,（3）在“lest（以免）；in case（以免）；for fear that（恐怕）”引导的句中：,Batteries should be kept in dry place lest electricity leak away（漏掉）.,虚拟形式：,(should +) 动词原形,6 .2 科技英语中虚拟语气的主要形式,3、在某些状语从句中,（4）有些人在“in order that”引导的从句中使用虚拟语气,In order that this expression（表达式）be a definite form（定界形式），the following condition is necessary and sufficient.,虚拟形式：,(shouldshall +) 动词原形,6 .2 科技英语中虚拟语气的主要形式,3、在某些状语从句中,（5）有些人在由“no matter ”引导的从句中使用虚拟语气,This equation holds, no matter what = whatever the independent variable（自变量）be.,虚拟形式：,(should +) 动词原形,6 .2 科技英语中虚拟语气的主要形式,4、表示客气或语气委婉,It would not be difficult to prevent road accidents（车祸）with the help of electronic apparatus（设备）.,虚拟形式：,shouldwouldcouldmight,+ 动词原形,6 .2 科技英语中虚拟语气的主要形式,4、表示客气或语气委婉,One might think that friction is always undesirable（不希望有的）.,虚拟形式：,shouldwouldcouldmight,+ 动词原形,6 .2 科技英语中虚拟语气的主要形式,*几个一般的考试中常考的句型：,Its time we began our class., “Its time + 定语从句（用过去时）”“该了”,6 .2 科技英语中虚拟语气的主要形式,*几个一般的考试中常考的句型：,涉及现在：, “wish if only + 句子”“但愿；要是就好了”,涉及过去：,I wish I had studied law at university.,从句用过去式,从句用过去完成式,6 .2 科技英语中虚拟语气的主要形式,*几个一般的考试中常考的句型：,涉及现在或将来：, “would had rather + 句子” “倒希望”,涉及过去：,They would rather we had not gone there yesterday.,句子用过去时,句子用过去完成时,
