根据上下文理解，选择所给词的适当形式填空。

   Yesterday was Sunday. We had no____ . I wrote a letter to my pen pal and____ lunch for my parents. After lunch I took a ____with Mike through the park behind my house. We saw a little girl____ for something. She lost her keys. “She ____  help,” Mike said. So we helped the girl look for her____ . About ten____  later, Mike found them in the grass. The girl was ____ . We spent much time in looking for the____ keys, but we____  very happy because we did a good deed（做好事）.

我们每天应喝适量的开水，这有利于（   ）。

如图为两种物质熔化时的温度―时间图像，根据图像，下列说法中错误的是