下图表示碳元素在无机环境和生物群落中的循环利用。请据图回答： （1）在高等植物叶肉细胞中，a过程发生的场所在 。b过程的发生
将4molA气体和2molB气体在2L的容器中混合并在一定条件下发生如下反应： 2A（g）+B（g）=2C（g），经2min后测得C的浓度为0.6mol/L则 （1）用物质A表示反应的
In the early nineteenth century, people had no idea ____ the inside of the earth might look like.A. that B. what C it D. which
Then why aren't you calm but trembling so much? The man with the gun asked angrily. Because I thought you were the ticket-collector, and I haven't even got a ticket, said John. 36. John
对下列现象解释不合理的是 A．在花园中可闻到花香——分子不断运动 B．将二氧化碳气体制成干冰，体积变小——分子体积变小 C．18g水中大约有6.02×10
．Play, often seen as ______ activity for kids, is still important in ____development of teenagers. A．the; the B．an; the C．an; 不填 D．the; 不填
文化大革命得以发动的根本原因在于 A党和国家面临资产阶级复辟危险 B“左倾”错误严重 C中央对内外形势估计过于严重
设数列满足:,,. (1)求数列的通项公式及前项和； (2)已知数列是等差数列,为的前项和,且,,求的最大值.
