情态动词也可以和动词进行形式或完成进行形式构成谓语:表示"应当正在……","想必正在……"的意思。
whyshouldwebesittingheredoingnothing?
shemightstillbethinkingaboutthequestionyouraised.
hecan’tbeswimminginsuchweather.
atthemomentshemay(might)beplayingwithherschoolmates.
weneedn’tbestandinghereintherain.wemighttakeshelterinthehutoverthere.
情态动词间或也可以和一个动词的完成进行形式构成谓语,表示"应当一直在……","想必一直在……"这类意思。
theyaresweatingallover.theymusthavebeenworkinginthefields.
theymayhavebeendiscussingtheproblemthismorning.
shecouldn’thavebeenswimmingallday.