新概念英语二册 Lesson32 Shopping made eas 第（4）套课件在线下载

So it was easier for the detective to watch her . 
The woman first bought a few small articles,  after a little time ,she chose one of the most expensive dresses in the shop and handed it to an  assistant who wrapped it up for her as quickly as possible .
Once adv . 
1)曾经；一度；从前
它是一个不确定的时间副词，其位置一般是在行为动词前，系动词后。
他曾经生活在美国，但现在他生活在英国。
He once lived in America, but now he lives in England. 
他的歌一度在年轻人中很流行。 
His song was once very popular among the young people. 
once用作副词，也可意为“一次”的意思。
两次是“twice”，三次是“three times”，四次是“four times”。 
对你来说只读一遍课文是不够的，你至少应该都三遍。
It’s not enough for you to read the passage once , you should read it at least three times .
注意once用作副词时，在句中的位置不同表示的意思也不同，需特别注意
I once went to Shanghai. 
我曾经去过上海。
 I went to Shanghai once. 
我去过上海一次。