来自沈晓华的问题
Thegirlhadhardlyrungthebell___thedoorwasopenedsuddenly,andherfriendrushedouttogreether.AbeforeBuntilCasDsince
Thegirlhadhardlyrungthebell___thedoorwasopenedsuddenly,andherfriendrushedouttogreether.
Abefore
Buntil
Cas
Dsince

