Whenhesawallhisbooks的精選

問題詳情：Whenhesawallhisbooks_____hereandthereonthefloor,heknewthatsomethingterrible_____.A.lying;musthavehappenedB.lie;musthappenC.lay;mighthavehappenedD.hadlain;couldhavehappen【回答】A知識點：動詞時態...