... tense changes Uses of the to-infinitive in indirect speech When we use indirect speech The infinitive and the '-ing' form The bare infinitive and the toinfinitive The bare infinitive ... the ending - for -fe into -ves in the plural with the following nouns: calf/calves, half/halves, knife/knives, leaf/leaves, life/lives, loaf/loaves, self/selves, sheaf/sheaves, shelf/shelves, ... and use of the causative Questions, answers, negatives YesINo questions, negative statements, YesINo answers Alternative negative forms and negative questions Tag questions and echo tags...