已知:a是97的因数,那么( )。
A:a只能是1
B:a只能是97
C:a是1或97
在DNA分子的一条单链中,相邻的碱基G与C是通过下列哪种结构连接起来的()
—I didn't hear you come in just now.
—That's good. We tried __________ any noise, for you were sleeping.
解释下列词语
①湖泊
②沼泽