Infinitives are known to encode covert modality in certain environments including infinitival relatives and questions. Beyond these environments, however, the precise distribution and interpretation of infinitival modality remains poorly understood. In that light, this paper investigates infinitive-embedding enough/too sentences like Pat is tall enough to be the thief or Lee is too old to drive. These sentences have a modal semantics whose compositional source is contested: on one approach, the infinitive encodes the modality, and on another approach, the enough/too morpheme itself is modal. To adjudicate this debate, I consider heretofore largely overlooked finite-clause-embedding enough sentences like Pat is tall enough that she might/must be the thief or Lee was fast enough that she won the race. They provide, I argue, novel support for the view that the modality is in the embedded clause (whether nonfinite or finite) and not in enough/too. I then compare the covert modality of nonfinite enough clauses to the covert modality of infinitival relatives, questions, and complements to attitude predicates and content nouns. I generalize that covert modality in nonfinite clauses never encodes epistemic necessity, and I tentatively hypothesize that this constraint reflects the marked status of nonfiniteness in the finite/nonfinite opposition.

已知不定式在某些环境中编码隐蔽模态，包括不定式亲属和问题。然而，除了这些环境之外，不定式模态的精确分布和解释仍然知之甚少。有鉴于此，本文研究了不定式嵌入的足够/太句子，例如Pat is high to be the thief或Lee is too old to drive。这些句子具有模态语义，其组成来源受到质疑：在一种方法中，不定式编码模态，而在另一种方法中，足够/太词素本身就是模态的。为了裁决这场辩论，我认为迄今为止在很大程度上被忽视的有限-从句嵌入足够多的句子，例如Pat 足够高以至于她可能/必须是小偷，或者Lee 足够快以至于她赢得了比赛。我认为，它们为模态存在于嵌入子句（无论是非限定的还是有限的）而不存在于enough / too中的观点提供了新的支持。然后，我比较了不定式从句的隐蔽模态与不定式亲属、疑问句以及态度谓词和实义名词的补语的隐蔽模态。我概括了非限定子句中的隐蔽模态从不编码认知必然性，并且我暂时假设这种约束反映了有限/非限定对立中非限定性的显着状态。