英语周报七年级外研2020~2021第17期答案

19.D)【解析】淀粉的组成元素是C、H、O,不含氮元素;本实验只做了4个不同氮素水平的实验,并不能得出随着氮素水平的升高,该植物光合速率持续增大的结论;氮素水平从300到600kg·hm-2时,植物的净光合速率变化不大不只是由于气孔导度的限制,还有色素含量的限制;从表格中已知净光合速率,若耍测定该果树叶片O2的产生量,即总光合速率,则还需在榘暗条件下测定叶片O2的吸收量。故选D。

Paragraph 1The boys had watched, open-mouthed, tohen their sisterplaced her favorite doll in the box. Without a word, theboys rose and went to their rooms and came back carryingtheir favorite toys to the living room. Astonished, I realizedthat the boys had also recognized what little Meghan'saction meant. I thought all of them wanted to make thesepoor people who had nothing happy like them. Swallowingback tears, I pulled all three of them into my armsParagraph 2I looked at my children for a long moment. I removemy old jacket from the box of clothes, too. I replaced itwith the new hunter green jacket that I had found on salelast week. I hoped the young woman in the picture wouldlove it as much as I did. What Meghan didson that the true spirit of dethheart

以上就是英语周报七年级外研2020~2021第17期答案，更多英语周报答案请关注本网站。