英语同义句转换口诀如下：
英语同义句转换是英语学习中的一个重要技巧，可以帮助我们更好地理解和运用英语语言。以下是一些常用的英语同义句转换口诀：
动词换形，意思不变；通过变换，名词、代词、形容词、副词以及介词等等都可能换形；尤其注意与数、级和某些介词构成的短语。
例如：The box is too heavy for the little boy to carry. 可以转换为：The little boy is too young to carry the heavy box.
某一词后介词省略，前提是该词后确能省略相应的介词；某些动词后能加宾语，修饰某一名词；使用时要注意不要漏掉后面的介词或宾语。
例如：He failed in the exam. 可以转换为：He didn't pass the exam.
某些常用的固定短语，如：only to do， be about to do， seem to do， what do you mean by， how do you like， as long as， as much as等。
例如：He didn't sleep last night. 可以转换为：He stayed up late last night.
注意下面的短语：up to now, until now, for the past few years, during the past few years, in recent years, recently, at present, at the moment, at the same time等。
例如：He has studied English for five years. 可以转换为：He began to study English five years ago.
总之，英语同义句转换需要我们掌握丰富的词汇和语法知识，并且能够灵活运用。以上口诀可以帮助我们更好地理解和运用英语语言，提高我们的英语表达能力。