8.牛乳房炎防治的策略上,每日飼料中硒(Se)之添加量應為多少?
(A)不用添加
(B)0.1 ppb
(C)0.2 ppb
(D)0.3 ppm
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統計: A(199), B(598), C(228), D(1101), E(0) #1739119
統計: A(199), B(598), C(228), D(1101), E(0) #1739119