哺乳动物细胞中DNA紫外线损伤最主要的修复酶是( )
A.DNA聚合酶αB.DNA聚合酶βC.DNA聚合酶γD.DNA聚合酶δE.DNA聚合酶ε
参考答案:E
Along with the letter was his promise _______ he would visit me this coming Christmas. [ ]
A. which
B. that
C. what
D. whether
大气过电压可分为()过电压和()过电压