我国去南极进行科学考察的最佳时间是每年的（  ）

（Ⅰ）求数列{a_n}的通项公式；

（Ⅱ）设b_n= $\{\begin{array}{c}\frac{{\log }_2{a}_n}{n^2\left(n+2\right)},n为奇数\\ \frac{n}{a_n},n为偶数\end{array}$ ，T_n为{b_n}的前n项和，求T_2n．

   The future can be difficult. There are many famous predictions 1 never came true.Before 1929, there was no sound in movies. The head of one of the2movie companies in the United States predicted that no one would want to see actors 3. Of couse,he was wrong! In 1979,the head of the largest computer company in the United States said,“No one will want to have a computer in his or her home.” He thought that computer would never 4by most people.