题干
—When are we going to see the movie ZooTopia, this afternoon or tonight?
— is OK. I'm free today.
A：Either
B：Neither
C：Both
D：All
答案(点此获取答案解析）
A
—When are we going to see the movie ZooTopia, this afternoon or tonight?
— is OK. I'm free today.
A：Either
B：Neither
C：Both
D：All
克隆抗体时，下列操作不必要的是（ ）