进行RFLP和PCR分析时,为保证酶切后产生RFLP在20kb以下,DNA长度要求短至()
A.40kb
B.50kb
C.60kb
D.70kb
E.90kb
参考答案:B
—________were you born, Kate?
—I was born in New York, America.
A.Where
B.What
C.When
D.How
根据《本地通信线路工程设计规范》,杆路上架挂的电缆吊线不宜超过二条。一条吊线上只宜挂设一条电缆。如距离很短,电缆对数小,可允许一条吊线上挂设二条电缆