The keeper of the spring cleared away the leaves and branches, and wiped away the silt(淤泥) that would have choked and polluted the fresh flow of water.
A. thus
B. otherwise
C. therefore
D. later
网友回答
A. thus
(答案→)B. otherwise
C. therefore
D. later
解析：A. thus因此，B. otherwise否则，C. therefore因此，D. later后来，句意：泉水的守护者清除了树叶和树枝，挖掉了如果不去掉就会堵塞污染清澈的水流的淤泥。这里用otherwise相当于if it hadn’t been wiped away，所以选B。