【单选题】下图表示叶绿体色素吸收光能的情况,根据此图并结合所学知识,以下说法中正确的是 ①叶绿素a对420nm、670nm波长的光的转化率较高 ②在晚间用大约550nm波长的绿光照射行道树,目的是通过植物光合作用以增加夜间空气中的氧气浓度 ③据图可知,用白光中450nm左右波长的光比白光更利于提高光合作用强度 ④在层析液中,类胡萝卜素的溶解度大于叶绿素 ⑤土壤中缺乏镁时,420nm~470nm左右波长的光的...
【简答题】阅读理解。 In Canada and the U.S.A, people enjoy entertaining (请客) at home. They often invite friends over for a meal, a party, or just for coffee and a conversation. Here are the kinds of things people sa...
【单选题】某同学测量的RC放电曲线和曲线拟合结果如图所示,拟合函数设为 ,下列表述正确的是
A.
表明实验测得的时间常数 =1/0.3626=2.758s
C.
表明实验测得的半衰期 =1/0.3626=2.758s
【简答题】阅读理解。 In northern China during spring big sandstorms often make trouble for people. Sandstorms usually happen in spring. They have happened in more than 10 provinces in northern China this year. Peopl...
【简答题】阅读理解 In the U.S.A. or Canada, on Sundays many people go out for a picnic. They often ask their good friends to go with them. They bring many things with them, li ke glasses, kites, knives, some nice f...