题干

小刚和同学利用青菜幼苗(如图甲)进行了植物向光性实验,他把等重,已发芽的青菜种子均匀地排列在4个培养皿中,当青菜幼苗升高至1.5厘米左右时,对各培养皿中的幼苗进行不同的处理,并都用单侧光连续照射一段时间,如图乙所示.

上一题 下一题 0.0难度 选择题 更新时间:2020-01-13 12:36:35

答案(点此获取答案解析)

同类题2

阅读下面短文,从短文后各题所给的四个选项(A、B、C、D)中,选出可以填入空白处的最佳选项,并在答题卡上将该项涂黑。

    People say one man's trash(垃圾) is another man's treasure. That1 comes to me as I2 the house purchased in 1962 by my parents. My mother passed away in 1996. My father left the house3 my sister and me when he died a few months ago.

    After Dad was4 , we looked around the5 house where we grew up and that Dad loved so much. At first we felt so6 all the stuff left. Like so many of their generation, my parents7 everything. And like many in my generation, we faced anxious 8 about what to abandon and what to keep.

    As we started throwing out old phone books and every medical bill from every9 my parents ever saw, I also10 many hidden treasures. Mom's pocketbook was in their bedroom closet, which had everything in it, 11 her hairbrush with hair, as if she were still here. And Dad, who was a World War II veteran(退伍兵) and a world traveler,12 everything—from little spoons from all over the world to every letter he wrote to his parents while in the13. The letters he wrote during the war14 his thoughts as a young man. Later, in the basement, I15 our old kitchen table, which brought back 16 of my parents and sister and me having breakfast together .

    I'm realizing all these things17 my parents' life journey. Each time I go to18, I find something that reminded me of my childhood or teaches me something about my parents I19 knew. 20, from the shabby furniture to all the hidden treasures, means more to me than all the money in the world.