题干

下列关于叶片中的光合色素的说法正确的是(    )

A:叶绿素对绿光吸收最多,所以叶片呈现绿色

B:用纸层析法分离色素,色素带从上至下依次是叶绿素a、叶绿素b、胡萝卜素、叶黄素

C:提取色素时应使用75%的乙醇,且在研磨碎叶时应加入少许二氧化硅和碳酸钙

D:温室或大棚种植蔬菜时应选用无色透明的玻璃,不应使用红色或蓝紫色的玻璃

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答案(点此获取答案解析)

D

同类题4

请认真阅读下面短文,从短文后各题所给的A、B、C、D四个选项中,选出最佳选项。

    Ever since I moved to Beijing in August, people have been telling me about the Fragrant Hills—1the autumn views they offer.

    So last Sunday I2 two poor, simple laowai . We looked forward with childish3 to golden leaves and the pleasant 4 of the pines in the crisp October air. After an hour-long subway and taxi ride, we found ourselves on a vast ring road interchange, boiling with traffic and people coming from all 5. It seemed that all China had decided to 6 to the Fragrant Hills that day.

    The words “Fragrant Hills” paint a picture of natural 7 and harmony—not rows of shops and 8 vendors (小贩) screaming at you to buy their goods.

    After half an hour of 9 through the sea of bodies, we made it into the park. All pretences (假装) of polite “Britishness” were washed away as we 10 moved people aside with two hands—the only way of making progress. A couple of times, we attempted a bit of walking 11 the path, only to be stung (刺) by poison ivy. We sadly returned to the12. Then suddenly, just past a temple, we caught sight of a dirt track. The people 13. We were the only ones there. There were14 golden leaves and peaceful pine forests. After that we, extremely 15, collapsed (倒) onto rocks and brought out our lunchboxes.

    16 the time came when we had to grit (咬紧) our teeth and throw ourselves17 again. It took another half hour of fruitless 18 before we could collapse into a taxi. At about 7 pm, I finally arrived at my 19 station, home sweet home, exhausted and aching. I had found my Fragrant Hills, my oasis (愉快之处) of 20, my harmony—in Chaoyang district.