We Need LF Copying: A Few Good Reasons Why

In sluicing, an interrogative clause is phonologically reduced to a wh-phrase (the ‘wh-remnant’). The wh-remnant can, but need not, have an overt correlate in the antecedent, as illustrated in (1) and (2). (1) a. Sam is drinking something, but I don’t know what. b. … I don’t know what <Sam is drinking>