SPECULATION& DEDUCTION CERTAINTY
Wecanuse“must”,“can’t”and “couldn’t”toexpressthatwearefairly certainaboutsomething
Forpresentsituation,themodal verbs“must”“can’t”and“couldn’t” arefollowedbytheinfinitivewithout to.
Ihaven’tsleptfortwodays. Youmustbeexhausted!
Icanhearsinging,sowecan’tbefar fromthestadium.
Thecontinuousformcanalsobeused.
Whyishewearinghisuniform? Hecouldn’tbegoingtoschool–it’s Saturdaytoday.
Forpastsituationsweusethesame modalverbs+have+pastparticiple (theperfectinfinitivewithoutto).
Ican’tfindmybook. Imusthaveleftitatschool.
Thisessayispoor. Youcan’thavespentlongonit. Thecontinuousformcanalsobe used.
Theroad’swet. Itmusthavebeenraining.
“mustn’t”isnotnormallyusedto makedeductionsaboutpresentorpast situations.Weusecan’tinstead.
We’vebeenwalkingforhours. Itcan’tbefarfromhere.
(NOTItmustn’tbefar)
POSSIBILITY
Ifwearenotcertainaboutsomethingbut thinkitispossible,wecanuse“may(not)”, “might(not)”,or“could(butnotcouldnot).”
Forpresentsituation,thesemodalverbs arefollowedbytheinfinitivewithoutto. Thecontinuousformisalsopossible.
John’snotansweringmyemails. Hemightbeonholiday.
Hecouldbetellingthetruth,butit’s hardtobelieve.
Forpastsituationsweusethesame modalverbs+have+pastparticiple (theperfectinfinitivewithoutto). Thecontinuousformisalsopossible.
Ithinkwemayhavetakethewrongroad. Thisdoesn’tlookfamiliar.
Samlookedsad.Hemightnothavebeen feelingwell.
Note:Itisnotpossibletouse“can”when speculatingaboutpresentorpastsituations.
-formingnegatives
Negativesareformedbyadding‘not’after themodalverbs,notaftertheauxiliaryhave. :modal+not+have+pastparticiple modalnothavepastparticiple
✓Hemaynothave beenthere
✗Hemayhavenot beenthere.