He said he had nothing ______ to say.
A. further
B. farther
C. less
D. any most
查看答案
He said he had ______ to tell the manager.
A. important something
B. important nothing
C. anything important
D. something important
He can swim______.
A. as fast as Tom, if not faster than
B. as fast as, if not faster than, Tom
C. as fast, if not faster, as Tom
D. faster, if not as fast as Tom
菌种衰退的原因可能是
A. 基因突变
B. 连续传代
C. 不适应的培养条件
D. 不适宜的保藏条件
菌种衰退的防治措施包括
A. 合理的育种
B. 选用合适的培养基
C. 创造良好的培养条件
D. 控制传代的次数
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