题干

研究发现,砷(As)可以富集在植物体内,转化为毒性很强的金属有机物,影响水稻的株高、根长和干重;加P(与As原子结构相似)处理后水稻茎叶和根中P含量增加、As含量相对减少,水稻生长加快,干重增加.对此现象不合理的解释是(  )

A:As在水稻细胞内富集,由细胞膜的结构特点决定

B:As进入水稻细胞,导致有关酶失去活性,影响代谢细胞

C:P影响As的吸收,与细胞膜上的载体种类和数量有关

D:P是构成磷脂、核酸和ATP的重要元素,能促进水稻生长发育

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A

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    Recently, my mother asked me to drop off some letters at the post office and pick up some stamps for her. Without giving it a thought, I took the letters and purchased her stamps.

    A few days later, she mentioned that one of the letters I had mailed was missing a stamp, and asked me if I had put a stamp on it. She had remembered asking me to put a stamp on it, though I certainly had not heard her. So, unfortunately, it looked like the letter, which was a bill of course, would come back marked "Return to Sender for Insufficient Postage". A few days went by and I returned to the post office to pick up our mail. While I was there, I saw the postmaster and happened to tell him about Mom's letter missing the stamp. I asked him to be on the lookout for it coming back. It was then that he told me his story. "You know," he said, "I immediately saw after you had dropped the mail off that your letter was missing a stamp. I also noticed that it was a bill for a credit card company. I thought to myself that you have always been kind to me and my partner, and I wanted to return the favor. So, to prevent your mother from getting charged a late fee from the credit card company, I took money from our change dish (extra pennies for folks who need one), and purchased a stamp for you."

    When I heard it, I couldn't believe it. What a blessing that was! I thanked him over and over again for putting the stamp on the letter for us. Then, I immediately dumped(倾倒) all the change out of my purse and into the penny dish in order to help others out in the future. When I got home, I was able to tell Mom the good news. This was kindness karma(因果报应) in action, I believe!