微生物杂交育种包括那些？
参考答案：
细菌的杂交育种、放线菌的杂交育种、霉菌的杂交育种、酵母的杂交育种.
You should go over your test paper _____ you hand it in.
A．before
B．though
C．because
D．as soon as
重力作用可造成
A．分层B．转相C．酸败D．絮凝E．破裂
