在学习“as...as”结构时，有几点需要特别注意：
- 理解含义：“as...as”是一个同级比较结构，表示“和……一样”。例如，“He is as tall as me.”（他和我一样高。）
- 词性使用：在“as...as”结构中，第一个“as”是副词，用来修饰后面的形容词或副词原级；第二个“as”是连词，用来连接两个相同的成分进行比较。
- 否定形式：在否定句中，第一个“as”可以替换为“so”，构成“not as/so...as”结构。例如，“She is not as/so beautiful as her sister.”（她没有她姐姐那么漂亮。）
- 数量或程度的比较：当涉及到数量或程度的比较时，可以使用“as much 不可数名词 as”和“as many 可数名词复数 as”的结构。例如，“I have as many books as you.”（我有和你一样多的书。）
- 形容词的位置：当“as...as”结构中间接形容词时，有时该形容词还可以修饰另一名词，但这个名词应带有不定冠词，且要注意词序。例如，“I have as good a voice as you.”（我的声音和你一样好。）
- 修饰成分的位置：如果有修饰成分，如“twice”、“three times”、“half”、“a quarter”等，应置于第一个“as”之前。例如，“He is twice as old as she.”（他的年龄是她的两倍。）
另外，还需要注意在实际语境中正确运用“as...as”结构，避免与其他相似结构混淆，例如“more...than”等。通过大量的练习和实际运用，可以逐渐掌握并熟练运用这一结构。
最后，建议学习者在掌握基本用法的基础上，多阅读英语文章，注意“as...as”结构在实际语境中的运用，从而加深对这一结构的理解和掌握。
练习题
1. 完成句子：
(a) She sings _______ _______ as her sister.
(b) My car is _______ _______ fast as yours.
(c) He is not _______ _______ smart as you think.
2. 改写句子，使用“as...as”结构：
(a) My dog is very fast. Your dog is also very fast.
(b) She has a lot of books. I have a lot of books too.
(c) My brother is tall. My friend is tall as well.
3. 填空：
(a) I have _______ _______ friends as you do.
(b) She doesn't eat _______ _______ vegetables as her brother.
(c) This movie is not _______ _______ interesting as the last one we watched.
4. 选择题：
(a) My room is _______ big _______ yours.
A. as; as B. so; as C. not; as D. as; so
(b) She can run _______ fast _______ a cheetah.
A. as; like B. so; like C. as; as D. so; as
(c) He is _______ old _______ to drive a car.
A. not as; enough B. as; enough C. not enough; as D. enough; as
答案
1. 完成句子：
(a) She sings as well as her sister.
(b) My car is as fast as yours.
(c) He is not as smart as you think.
2. 改写句子，使用“as...as”结构：
(a) My dog is as fast as your dog.
(b) She has as many books as I do.
(c) My brother is as tall as my friend.
3. 填空：
(a) I have as many friends as you do.
(b) She doesn't eat as many vegetables as her brother.
(c) This movie is not as interesting as the last one we watched.
4. 选择题：
(a) A. My room is as big as yours.
(b) C. She can run as fast as a cheetah.
(c) A. He is not as old as to drive a car.
