一块平行四边形菜地，底是55米，高32米．如果4平方米可收白菜120千克．这块地共可收白菜____千克

下列物质中含有氧气分子的是（   ）

阅读短文，回答下面的问题。
    I'm John．My father's birthday is on January 5th．My mother's birthday is in January，too．My birthday is on April 4th．My brother's birthday is on November 2nd．Today is my sister's birthday．Her birthday is on October 3rd．It's her eleventh birthday．I buy a big cake for her．We have a birthday party in the evening．

1953年，中国提出和平共处五项原则，当时主要是为了

在各项均为正数的等比数列$\left\{a_n\right\}$中,公比$q\in (0,1)$．若$a_3+a_5=5$,$a_2{a}_6=4$ ,$b_n={\log }_2{a}_n$数列$\left\{b_n\right\}$的前$n$项和为$S_n$,则当$\frac{S_1}{1}+\frac{S_2}{2}+...+\frac{S_n}{n}$取最大值时,$n$的值为（   ）