铁氧化细菌能氧化(),硫氧化细菌能氧化()。
A.铁
B.钙
C.钠
D.硫
参考答案:A, D
.The terrible flood swallowed the village ________ the villagers could get away. No one survived it.
A.after
B.as
C.since
D.before
法的实效