MODAL VERBS DEDUCTION
MUST We use MUST to say that you believe that something is certain: You’ve been travelling all day, you must be tired. I’m sure he gave me his telephone number. I must have it somewhere
CAN’T We use CAN’T to say that you believe that something is not possible: She can’t be her mother, she is too young. You’ve just had lunch. You can’t be hungry!
MAY/MIGHT We use MAY or MIGHT to say that something is a possibility: John is not at work today. He may/might be ill. ‘Where is Tom?’ ‘I don’t know. Ask Mary, she may/might know’ Peter is not at home. He may/might be in his office
PAST We use the following structures: MUST HAVE + PAST PARTICIPLE He doesn’t find his keys. He must have left them in the office (he’s always doing that!) CAN’T HAVE + PAST PARTICIPLE She can’t have left her boyfriend. She was madly in love with him! MAY/MIGHT HAVE + PAST PARTICIPLE ‘Kate didn’t answer the phone yesterday’ ‘Don’t worry, she may/might have been asleep’