题干

某校园内设置了“小草依依,踏之何忍”的提示语牌,以提醒人们不要践踏小草,否则会造成土壤板结,而影响草的生长.其主要原因是(  )


A:植物缺少无机盐,影响生长

B:植物缺少水,影响光合作用

C:气孔关闭,影响蒸腾作用

D:土壤缺少氧气,影响根的呼吸

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答案(点此获取答案解析)

D

同类题3

阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。

    It was a bad time for me. I was low emotionally and tired physically. Probably because of this I hadn't shaved for a few days. Also, because I had been doing some repairs at my daughter's house, I was dressed quite scruffily(不整洁地). Boarding the bus to go home I saw it was almost full so I found a rail(扶手) to lean against.

    That's when a young woman, sitting with her child, stood up and offered me her seat. ‘Wow!' I thought. Out loud I said, “Do I look that old and tired?” She replied, “You look like you've had a tough day.” I thanked her sincerely and stayed standing.

    A moment later a man rose from his seat at the back of the bus and made his way towards me, walking past several people on the way. Then he told me about his addiction(毒瘾) problems, asked my advice, and just chatted about life for a few minutes. Then he went back to his seat. Very random!

    Watching him go, I also looked at the bus-load of people between me and his seat. He hadn't chosen to talk to those strangers. He chose to talk to this stranger, for whatever it meant to him and whatever comfort it brought him. Why?

    That's when it occurred to me. I must have looked like I had been where he was. I probably looked like a man who would understand a difficult life. I was humbled(谦卑的) and encouraged at the same time by the realization that even when we are at our lowest we can still help others — if we look like we might be able to meet them where they live or walk a while in their world.