题干

下列有关实验课题与相应方法的叙述,错误的是(  )

A:观察叶绿体利用健那绿染液将叶绿体染成蓝绿色,再用显微镜观察

B:分离细胞器利用了差速离心法

C:细胞膜的制备利用蒸馏水使哺乳动物的成熟红细胞吸水涨破

D:蛋白质遇到双缩脲试剂可形成紫色络合物

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答案(点此获取答案解析)

A

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    My wife Pat and I were having drinks outside our home, The weather was unusually1for March in Mississippi, There was barely any breeze, After we finished the second cup, flashes of2danced across the sky. When the first drops of rain drove us3 the phone rang.Pat's face4on that gray and hot day. It was our son, David, a helicopter pilot who5in the US Air Force in South Korea. David intended to sound6but we recognized the sign of homesickness from his voice7the power of conversation made us feel8until a crash shook the windows.

    David wondered what it was,“Just thunder,”Pat said.

    There were several seconds of silence,“David”,I asked, “are yo9there?”

    “Yes…apart from the two of you, do you know what else I10most? Thunder, We have rain, wind, and11here, but it never thunders, Remember? Dad, when I was a kid, you laughed me out of fear of thunder? I wish I were there to12with you now.”

    “Yes…”I said, trying to13my tears, On hanging up the phone, I told Pat,“I'm going to record our son some 14”“Bob, the neighbors will think you're crazy.”

    “David won't,” I said and went outside with a recorder, Later I15the tape to David with a single line:A16gift.

    David called again, “Dad,”he said,“you won't believe that some friends and I had a thunder party where we realized we were listening to the sounds of 17 Thanks, Dad! It was really a special present,” While David was in Korea, we found ourselves 18thunderstorms.19feeling blue, we regarded the thunder as special which let us know that wherever we might be, we were 20together as a family.