今天的句子：①Among other weaknesses, the measures cities must employ when left to tackle dirty air on their own are politically controversial, and therefore vulnerable. ②That’s because they inevitably put the costs of cleaning the air on to individual drivers — who must pay fees or buy better vehicles — rather than on to the car manufacturers whose cheating is the real cause of our toxic pollution.
单词：
weakness英/ˈwi:knəs/ n.虚弱，软弱；缺点，不足；疲软
employ英/ɪmˈplɔɪ/ v.雇用；使用，利用
tackle英/ˈtæk(ə)l/ v.应付，解决（难题或局面）
dirty air污浊空气
on one’s own独立地；独自地；主动地
politically英/pəˈlɪtɪkli/ adv.政治上
controversial英/ˌkɒntrəˈvɜːʃ(ə)l/adj.有争议的，引发争论的
vulnerable英/ˈvʌlnərəbl/ adj.（身体或精神）脆弱的，易受伤的；（事物、人或地方）易受攻击的
inevitably英/ɪnˈevɪtəbli/ adv.不可避免地，必然地；意料之中
fee英/fiː/ n.费用，酬金；会费，入场费
vehicle英/ˈviːəkl/ n.交通工具，车辆
manufacturer英/ˌmænjuˈfæktʃərə(r)/ n.生产商，制造商
toxic英/ˈtɒksɪk/ adj.有毒的，引起中毒的；令人极不愉快的
断句
①Among other weaknesses, //the measures //cities must employ //when left to tackle dirty air //on their own //are politically controversial, //and therefore vulnerable.
语法解析：
1）主句：Among other weaknesses(状语), //the measures（主语）…. are（系动词）+ politically（副词做状语） controversial（表语1）, //and therefore（插入语）+ vulnerable（表语2）.
翻译：除了其他缺点外，措施存在政治争议，因此也易受攻击。
2）定语从句：（that）cities（主语）+ must employ（谓语）
备注：引导词代指measures在从句中作employ的宾语
3）时间状语从句：when（引导词）+（cities are）+ left to tackle dirty air //on their own
翻译：城市在独自处理空气污染时
备注：这里是状语从句的省略情况，原来的句式结构是
Cities must employ the measures whencities are left to tackle dirty air on their own
补充语法知识点在文章末尾处：
翻译：
①Among other weaknesses, //the measures //cities must employ //when left to tackle dirty air //on their own //are politically controversial, //and therefore vulnerable.
除了其他缺点外，城市在独自处理空气污染时必须采取的措施存在政治争议，因此也易受攻击。
②That’s //because they inevitably put the costs of cleaning the air //on to individual drivers //— who must pay fees or buy better vehicles — //rather than on to the car manufacturers //whose cheating is the real cause of our toxic pollution.
语法解析：
1）主句：That’s（主语+系动词）
翻译：这是
2）表语从句：//because（引导词）+ they（主语）+ inevitably（插入语）+ put（谓语）+ the costs of cleaning the air（宾语）+ on to（介词）+ individual drivers（宾语） ….rather than（并列连词）+ on to the car manufacturers（宾语）
翻译：
1）因为他们必然让个人司机承担了净化空气的成本而是让汽车生产商来承担
2）因为他们必然把净化空气的成本推给了个人司机而不是汽车生产商
3）定语从句：//— who（引导词代指individual drivers） must pay （谓语）+fees （宾语）+or（并列连词）+ buy（谓语）+ better vehicles（宾语） — //
翻译：------他们必须支付费用或购买更好的汽车------
4）定语从句： //whose（引导词作定语）+ cheating（主语）+ is（系动词）+ the real cause（表语）+ of our toxic pollution（后置定语）.
翻译：他们的欺骗行为才是有毒污染的真正原因。
翻译：
①Among other weaknesses, //the measures //cities must employ //when left to tackle dirty air //on their own //are politically controversial, //and therefore vulnerable.
②That’s //because they inevitably put the costs of cleaning the air //on to individual drivers //— who must pay fees or buy better vehicles — //rather than on to the car manufacturers //whose cheating is the real cause of our toxic pollution.
①除了其他缺点外，城市在独自处理空气污染时必须采取的措施存在政治争议，因此也易受攻击。②这是因为他们必然让个人司机承担了净化空气的成本-----他们必须支付费用或购买更好的汽车------而不是让汽车生产商来承担，他们的欺骗行为才是有毒污染的真正原因。
全部合在一起一起翻译：
②That’s //because they inevitably put the costs of cleaning the air //on to individual drivers //— who must pay fees or buy better vehicles — //rather than on to the car manufacturers //whose cheating is the real cause of our toxic pollution.
②这是因为他们必然让个人司机承担了净化空气的成本-----他们必须支付费用或购买更好的汽车------而不是让汽车生产商来承担，他们的欺骗行为才是有毒污染的真正原因。
当状语从句的主语与主句的主语一致时且从句中含有BE动词的某种形式时，可以省略状语从句的主语和系动词be ，这时从句中可出现如下结构：
① 连词（as, as if , once）+ 名词
如：Once (he was)a worker ,Pang Long now becomes a famous singer .
庞龙曾经是个工人，现在变成一位著名的歌手。
②连词（ though, whether , when）+形容词
如：Work hard when (you are) young ,or you'll regret.
趁年轻要努力学习，要不然你会后悔的。
③连词(whether, as if ,while )+介词短语
如：He looked everywhere as if (he was)in search of something .
他到处看似乎在找什么东西。
④连词(when , while , though )+ 现在分词
如：While (he was) holding talks with President Hu Jintao , US President George W. Bush thanked China for its important role in the Six-Party Talks.
美国总统布什在与胡锦涛主席会谈时，感谢中国在六方会谈中起的重要作用。
⑤ 连词(when ,if ,even if ,unless ,once ,until, than , as ) + 过去分词
如：The exhibition is more interesting than (it was) expected .
这次展览比被预料的有趣的多
⑥ 连词(as if ,as though ) + 不定式
如：Olympic gold medallist hurdler Liu Xiang opened his lips as if (he were) to speak .
奥林匹克金牌获得者跨栏运动员刘翔张开嘴好象要说什么。
（2）当从句的主语与主句的主语不一致，但从句主语是 it，从句中又含有系动词be 的某种形式时 ，可以把it和系动词be一起省略。。
如：Unless (it is) necessary ,you'd better not refer to the dictionary.
如果没有必要，你最好不要查字典。
