Modal Verbs: Speculating about past events1. SPECULATIONS ABOUT THE PAST100 % certain

We often speculate, or make best guesses, about past situations based on facts that we have. Themodalthat we choose depends onhow certainwe are about our speculation.AffirmativeMust haveHad to haveMay haveMight haveCould haveNegativeCant haveCouldnt haveMust not haveMay not haveMight not have

0% certain

When you arealmost 100 percent certainthat something waspossible, usemust haveorhad to have.The statues are very big.SpeculationTheymust have beenhard to move.

When you areless certain, usemay have, might have, orcould have.The islanders were able to carve the stone.SpeculationThe stonemay have beenquite soft.

When you arealmost 100 percent certainthat something wasimpossible, usecant haveorcouldnt have.The islanderscouldnt have movedthe stone! It was too heavy.

When you areslightly less certain, usemust not.Theymust not have movedit without help.

Usemay not haveormight not havewhen you areless certain.The islandersmight not have movedthe statues over land. They could have used boats.

There is a man badly injured in the hospital. Complete what his friends are saying about him, using each of these verb forms.couldntmay havemay notcouldmaymight have

He __________ be in hospital for weeks.He __________ recover completely.But it ___________ be worse. He ____________ been killed.This is a very good hospital. He ___________ get better medical treatment anywhere else.The other car was on the wrong side of the road. The driver ___________ been drunk.

So, there we have it. As Sherlock Holmes said, when you have eliminatedthe impossible, whatever remains,however improbable, must be the truth. I guess in this case, it was pretty darn probable, though.THE GRAMMARWe can useMODALStospeculatein English. The Modals for speculation are:must,could,may,may not,might,might not,cant,andcouldnt.We can put thesemodals of speculationinto 3 categories. We categorize them byhow certainwe are.#1) If we are very certain that something is true (95%-99%), we usemust.For example: Shemust have stolenthe cake!(PAST TENSE CERTAINTY:MODAL+have+PAST PARTICIPLE) Whoever it wasmust bea chocolate lover.(PRESENT TENSECERTAINTY:MODAL+BF)#2) If we are talking about things we believe are possibilities (30%-50%) we usecould, may, may not, might, and might not.For example: Anyonecould have takenthe cake. (PAST TENSE POSSIBILITY:MODAL+have+PAST PARTICIPLE) Itmay have beenhim, but he seems to like cookies. (PAST TENSEPOSSIBILITY:MODAL+have+PAST PARTICIPLE) So I guess, itmight not have beenhim.(PAST TENSE NEGATIVEPOSSIBILITY:MODAL+not+have+PAST PARTICIPLE)#3) If we are very certain that something isimpossible,we usecantorcouldnt.For example: Thatcant beright-The witness said the suspect was average size.(PRESENT TENSE IMPOSSIBILITY:MODAL+not+BF) And itcant have beenthis guy. He only likes vegetables!(PAST TENSE IMPOSSIBILITY:MODAL+not+have+PAST PARTICIPLE)NOTICE!cantandcouldntare bothpresent and past! Past Modals of Speculation change tense by adding eitherBFORhave+PAST PARTICIPLE.Therefore could is not necessarily past, and cant is not necessarily present.