Whenhesawallhisbooks的精选

问题详情：Whenhesawallhisbooks_____hereandthereonthefloor,heknewthatsomethingterrible_____.A.lying;musthavehappenedB.lie;musthappenC.lay;mighthavehappenedD.hadlain;couldhavehappen【回答】A知识点：动词时态...