In Gerunds^x, Present perfect^x, Simple past^x

1) Where are you? I've been waiting for 2 hours2) I needn't have brought that milkI = subjectneed have bought = verb; present perfect tense, modal form (need is the auxiliary), buy is the main verb, bought is the past participle.not - adverb that - demonstrative pronoun refering to...

Simple present. They all form a logical pattern. You are wrong about present perfect, by the way. am, is, are + -ing Present continuous was, were + -ing Past continuous am, is, are + anything else Simple present was, were + anything else Simple past has, have + been + -ing ...