[语法初识]

原句感知 自主探究 ①Norway is at the top of the list, while the US is at number 7.

②You can do it however you like.

③In the last ten years in China, 150 million people moved out of poverty. However, the challenges are still great.

④The report shows that we are making some progress but that we need to make greater efforts.

⑤Although developed countries give some financial help，they need to give much more.

⑥Fast as/though you read, you can't finish the book in three days.

⑦While he is in poor health, he works hard. 1.由句①④可知，while, but可用作并列连词，表示转折关系。

2．由句③可知，however表示转折意义时，常作副词，作插入语。

3．由②⑦可知，however, while还可用作从属连词，引导让步状语从句，分别意为：无论；尽管。

4．由句⑤⑥可知，as, though, although引导让步状语从句，当把as, though引导的从句置于句首时，句子常采取倒装语序，(though引导的从句可不倒装)。 　　

　　[语法剖析]

语法点一 表示转折关系的however, but与while 　　

　　1．however

　　however用作副词时，意为"然而，不过"。它的语气比but弱，不直接引出相反的意见，可放于句首和句中，且通常用逗号与句子其他成分隔开。

His first response was to say no. Later, however, he changed his mind.