Someone must have entered the room, the door has been unlocked． A.sinceB.asC.bec
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Someone must have entered the room, ______ the door has been unlocked．
A.since
B.as
C.because
D.for
试题答案
D
Someone must have entered the room, ______ the door has been unlocked．
A.since
B.as
C.because
D.for
D