混床再生时，反洗分层的好坏主要与反洗分层时的阀门操作有关，与树脂的失效程度无关。（）
参考答案：错
— Are these your books?
— _____ . They are Sally's.
[ ]
A. Yes, these are
B. Yes, they are.
C. No, these aren't
D. No, they aren't.
真菌杂交育种的理论基础，需注意的基本问题及育种的步骤？
