1.the cycle of the tide occures twice every 24 hours and is _on the moon
A .evident B.dependent C.indenpent D.subsequent
选 B
A.evident,形容词,明显的,用法是 be evident to/ that 从句
B.dependent,形容词,两层意思：1,依赖的,依靠的；2,取决于.用法是
be dependent on
2.It is not necessary to boil the drinking water,because it has already been __ chemically.
A.distilled B.cleared C .purified D.refined
选 C
3.The river is already __ its banks because of excessive rainfall and the town is threatened with a likely flood.
A level in B.flat on C.parallel to D.flush with
选 D
4.The space Age __ in the Oct 1957 when the first artificial satellite was launched by the Soviet Union.
A.embarked B.initiated C.commenced D.originated
选 B