①叶片在暗处放置时间过短，有机物未被耗尽　②曝光时间过长，有机物发生了转移

③叶片未用酒精脱色处理，绿色对蓝色造成的干扰　④曝光时间过短，有机物生成的数量过少．

1910年，丹麦科学家詹森在前人探索的基础上，对植物的向光性进行了进一步探究（如图）。下列有关詹森探究实验的叙述中，正确的一项是（）

1982年，我国颁布第几部《中华人民共和国宪法》（   ）

下列实验能达到预期目的的是                               （　　）

     Mrs Smith is Jim's mother. She loves her family very much. She often buys food, fruit and clothes for Jim and his father. Now many clothes are on sale at a good price.
     Mrs Smith comes to the store and she wants to buy some clothes. They have sweaters in all colors for￥15 each and sports shores for only ￥28.Mrs Smith likes the red sweater and  she buys one for herself(她自己).She buys a pair of sports shores for her son. The T-shirts in the store are just ￥18! She buys a white one for Mr Smith. And that's not all. The socks, in all colors, are ￥2 each. She buys five pairs.