如图,在12×6的网格图中(每个小正方形的边长均为1个单位),⊙A的半径为1,⊙B的半径为2,要使⊙A与静止的⊙B外切,那么⊙A由图示位置需向右至少平移( )个单位.
2
ELISA中通常使用的酶是
A.核酸末端转移酶
B.以上均是
C.碱性磷酸酶
D.葡萄糖6磷酸酶
E.辣根过氧化酶
Configuration management system can be used in defining approval levels for authorizing changes and providing a method to validate approved changes.()is not a project configuration management tool.
A.RationalClearcase
B.QualityFunctionDeployment
C.VisualSourceSafe
D.ConcurrentVersions System