double adj. 加倍的，雙的 v. 加倍，增倍
[特徵]
a double bed 一張雙人床
- his debt is double what it was five years ago.
他的債務是五年前的兩倍。
- the money will double next year.
這些錢明年將翻一番。
[練習與解答]
- the price of vegetables has because of bad weather.
a. doubt b. doubted c. troubled d. doubled
答案：d
（因為糟糕的天氣，蔬菜的價格翻了一倍。double意為“增加一倍，翻一番”；doubt意為“懷疑，不相信”；trouble意為“麻煩，打擾”。）
doubt n. 懷疑，疑惑 vt. 懷疑，不信
[特徵]
- i have no doubt that he'll pass the exam.
我不懷疑他會通過考試。
- i doubt that he is telling a lie.
我不相信他在說謊。
[貼心叮嚀]
doubt非常重要。它既可作名詞也可作動詞，它的用法值得我們注意。
[備考必備]
①動詞doubt後常接名詞從句。在肯定句中，名詞從句由whether，if，when，what等來引導；而在疑問句及否定句中，用that來引導。
- it has been doubted whether the story is true.
有人懷疑這個故事是否屬實。
- i don't doubt that he will keep his promise.
我不懷疑這個故事是否屬實。
②doubt作名詞時，可以說there is no doubt that ...，但不能用it is no doubt that ...
（誤）it is no doubt that he is a rich man.
（正）there is no doubt that he is a rich man.
毫無疑問他是個有錢人。
③重要詞組
be in doubt about sth. 對某事不能確定
have doubts about (doing) sth. 懷疑（做）某事
no doubt 無疑地，很可能
- no doubt he is a hand some man.
毫無疑問他是個英俊的男人。
download v. 下載
[特徵]
- many movies can be downloaded from internet.
很多電影都可以從網際網路上下載。
[貼心叮嚀]
這個詞是伴隨著網際網路的發展而流行起來的，相信大家一定非常了解download這個詞。
downstairs adv. 在樓下；往樓下
[特徵]
fall downstairs 跌下樓
- mother went downstairs to answer the front door.
媽媽下樓去開前門。
（downstairs是副詞，而不是名詞，其前面不加介詞。）
- i went downstairs to have breakfast.
我下樓吃早飯。