人是____的，我们每个人都有很大的发展空间。

若将稀硫酸换为浓盐酸，实验中C装置增加的质量会偏大，请说明理由____ 。

如图，在△ABC中，点D、E分别是边BC、AC的中点，过点A作AF∥BC交DE的延长线于F点，连接AD、CF．

（1）求证：四边形ADCF是平行四边形；

（2）当△ABC满足什么条件时，四边形ADCF是菱形？为什么？

根据短文内容，完成下面各题。(每空一词)。

（C）

     One of Harry's feet was bigger than the other. “I can't find suitable shoes for them,” he said to his friend, Jack.

    “Why don't you go to a shoemaker?” Jack said, “A good one can make you the right shoes.”

    “I don't want to go to any shoemaker,” Harry said, “Aren't they expensive?”

     “No,” Jack said, “Some of them aren't. There's a good one in our town. Here's his address. ”

       Harry went to the shoemaker in Jack's town a few days later, and the shoemaker made him some shoes.

       Harry went to the shop again a week later and looked at the shoes. Then he said to the shoemaker angrily, “You are a foolish man! I told you to make one shoe bigger than the other, but you made one smaller than the other. ”