若`\alpha _1,alpha _2,alpha _3,beta _1,beta _2`都是四维列向量, 且四阶行列式`\| alpha _1,alpha _2,alpha _3,beta_1 | = m,| alpha _1,alpha _2,beta_2,alpha _3 | = n` 则`\| 2alpha _1,2alpha _2,2alpha _3,2(beta_1+beta_2) | =` ()A.`\ (m+n)`B.`\ 8(...