... negative prefixes in im-, un- and –in. 46 IELTS Foundation Student’s Book Answer Key 2 dis- not, or to reverse an action disloyal, disappear re- again, or back reprint, reverse trans- across transatlantic, ... illiterate (but note: disloyal) pre- before pre-war, premature micro- small microscope, micrometer 3 1 uni- 2 bi- 3 tri- 4 qua- 10 dec- 4 a) a bicycle with a single wheel b) to manage something badly ... weak have to ought to don’t have to ought not to 50 IELTS Foundation Student’s Book Answer Key 4 Present time Past time should should have + past principle have to had to + infinitive must had...