From perspective of a psycholinguist, discusses three leading questions that have arisen from foundational, descriptive second-language-acquisiton studies: Why are certain L2 constructions learnable and others not?; In considering input requirements, is it fair to say that adult learners can take advantage of metalinguistic information about the language and negative input?; Is focal attention required for acquisition of syntax and phonological rules of target language? (Author/JL)