A.12~24h B.24~36h C.36~48h D.48~60h E.12h
A.1/2 B.1/3 C.2/3 D.1/4 E.3/4
A.生長(zhǎng)發(fā)育迅速 B.體溫調(diào)節(jié)機(jī)能強(qiáng) C.消化機(jī)能不健全 D.抗逆性差 E.敏感易驚群,自衛(wèi)能力差