carefully的比较级是more carefully，最高级是most carefully。既然提到了carefully，下面来介绍一下和carefully有关的英语知识：
The more carefully you plan, the better the result will be. The more quickly a car is driven, the more likely it is to cause an accident. The harder you work, the more rapidly you will obtain …
A comparative adverb compares two actions or performances (e.g., Ian thinks more carefully than you). A superlative adverb compares three or more actions or performances (e.g., Jan …
解析. 选more carefully.原因：work在这里是动词,修饰动词是的副词,careful是形容词,carefully是副词.因此,排除有careful的选项.很显然,than before这里有一个比较的问题,因此要用比较级.四个选项中,只有more …
"Carefully" 是一个副词（adverb），用来修饰动词、形容词或其他副词，表示动作的方式是小心、谨慎或细致的。 例如，"He carefully examined the document"（他仔细地检查了文件）。 二 …
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