人教版高中英语配套ppt课件：选修6 unit 4 period 2精选.ppt

2．It is OK to leave an electrical appliance on so_long_as you are using it－if not，turn it off！只要你在使用电器设备，你便可以把它开着，如果不用就把它关掉！ (1)so long as(＝as long as＝only if)，意为“只要”引导条件状语从句。 As long as you drive carefully, you will be very safe. 如果你开车小心，你就会很安全。 【温馨提示】 So long as/As long as you have confidence in yourself，youll win.只要你有自信，你会获胜的。 as long as只能用于肯定句，而so long as既可用于肯定句又能用于否定句。as long as还可意为“与……一样长；长达……”。 This line is four times as long as that one. 这条线是那条线的四倍长。 We need a rope as long as 20 metres. 我们需要一条20米长的绳子。 (2)本句中if not是if you are not using it的省略形式。if后常跟so或not来代替上文内容。 Get up early tomorrow. If not (＝If you dont get up early)，you will miss the first bus. 明天早起，否则你将赶不上第一班车。 He may not be at home then. If so (＝If he is not at home)，leave him a note. 那时他可能不在家，要是这样的话，给他留张便条。 if possible　　　　 　 如果可能的话 if necessary 如果必要的话 if any 假如有；即使有 【单项填空】 ①Some of you may have finished Unit One.________，you can go on to Unit Two. A．If you may B．If you do C．If not D．If so 解析　考查省略句。句意：你们当中有些人可能已经完成了第一单元，如果这样的话，你们可以继续做第二单元。if not “如果不这样的话”；if so“如果这样的话”。由句意可知选D项。 答案　D ②—Our holiday cost a lot of money. —Did it? Well，that doesnt matter________you enjoyed yourselves. A．as long as B．unless C．as soon as D．though 解析　考查连词辨析。由对话语境可知，空格后的一句是空格前一句的前提条件。故A项意思相符。as long as只要。 答案　A ③You may use the room as you like________you clean it up afterwards. A．so far as B．so long as C．in case D．even if 解析　句意：你尽可随意使用这个房间，只要你过后打扫干净即可。so far as远到；so long as只要；in case 以防(万一)；even if即使。故B项符合句意。 答案　B 3．So if you are not using the lights, the TV, the computer, and_so_on，turn them off. 因此当你不用灯、电视、电脑等等时，将它们关上。 and so on用于不完全列举，相当于and so forth。 If you know a foreign language you can tell your foreign friends about your fami