不定式的完成形式(to)have done在中学语法中是一种较难掌握的现象。课本中出现的较少,语法描述也不够详尽。可是在不同问题中,不定式的完成形式却经常出现,给同学们理解和表达造成了障碍。本文旨在总结不定式的完成形式在使用中的规律,以帮助学习者形成知识结构,便于掌握和应用。 1.could+不定式的完成形式在肯定句中表示“本来能够…(没能)”;在否定句中,表示“本不可能本不可以(却做了)”之义。如: The infinitive form (to) has done in middle school grammar is a more difficult phenomenon to grasp. There are fewer textbooks and the grammar description is not exhaustive. However, in different issues, the incomplete form of the incomplete form often appears, which creates obstacles for the students to understand and express. The purpose of this paper is to summarize the rules of the use of incomplete forms of completion in order to help learners form a knowledge structure that is easy to grasp and apply. 1. The form of the incomplete incomplete form in the affirmative sentence means “has been able to ... (not able to)”; in the negative sentence, it means “this cannot be (but is done) impossible.” Such as: