【单选题】A variety of drugs can alter DNA replication in eukaryotic cells. Which one of the following steps could be a target for such a drug? Choose the one best answer.
A.
The enzyme family of DNA polymerases, which unwinds parental strands
B.
The enzyme family of topoisomerases, which copy each parental strand in the 3 ′ -to-5 ′ direction
C.
The enzyme family of helicases, which copy each parental strand in the5 ′ -to-3 ′ direction
D.
The finding that both strands of newly synthesized DNA always grow continuously
E.
The enzyme DNA ligase, which joins Okazaki fragments
【单选题】Choose which one of the four words most suitably fills the blank space. Attention: the same requirement goes to the following blank-filling questions .
A.
ey all take too much ____ of his kindness and generosity.