通过一个透镜观察印有字母的纸的情形如图所示．由图可知，该透镜属于 ____透镜．所成的像是缩小、倒立的 ____像．

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阅读下面短文，根据短文内容，从方框中选出恰当的单词，将其正确形式填入短文空白处。(每词限用一次)

what, pull, another, with, some, find,

still, decide, success, teacher

    A professor(教授) told his students to go into the city slums(贫民窟) to study the life of 200 boys. He asked them to write reports about each boy's life and future. One of the students wrote, “They don't have ____ hope．”

    Twenty-five years later，____ professor read about the earlier study. He told his students to find out ____ had happened to the boys. They tried very hard and ____ that 176 of the boys had become successful as doctors, teachers and scientists.

    The professor was very surprised and ____ to study it further．Luckily, all of them were living near the place and he was able to ask each one, “What made you successful? ” Each one answered, “It was a ____ . ”

    The teacher was ____ living there, so the professor found her and asked the old woman what she had done to ____ those boys out of the slums, and change them into  ____ people.

    The teacher's eyes began to shine and said ____ a sweet smile, “It's really very easy. I love those boys. ”

我们美丽的校园是一个生态系统，构成这个生态系统的是（   ）