ability advice agent annoyance arrangement aspect assumption causative certainty class clauses comparatives completion conditional continuous criticism developing state duration emphasis expectation fixed event form future general truth geographical names gerund habit hypothesis indirect speech infinitive intention inversion modal necessity numbers obligation offer participle passive past past participle perfect perfect infinitive period of time permission place names point of time possibility prediction present present participle prohibition proper names punctuation request simple state subjunctive suggestion superlatives temporary tense time unlikelihood unreal willingness