练习说明
句子填空 题目要求：阅读文段，从文中挑选原词补全句子，每道题目都有特定的字数要求，以黑体加粗字标示。请把答案填到每题空缺处。
Choose NO MORE THAN TWO WORDS AND/OR A NUMBER from the passage for each answer.
第 1 题
Eduardo Neves, an archaeologist at the University of São Paulo in Brazil, has been studying these vanished cultures for 17 years, and from his discoveries in the Amazon rainforest, he is convinced that the rainforest was relatively densely populated between 500 and 1,000 years ago.
From the theories, the population of each settlement may have been more than _______________
第 2 题
Heckenberger and his team have combed the rainforest around the upper reaches of Rio Xingu since 1993 and, aided by satellite imagery, have found evidence of 28 settlements, these lie in an area of 20,000 square kilometres, and were once linked by roads.
Satellite imagery shows that _______________ connected settlements.
第 3 题
Darwin thought it incredible that brushing a leaf with a single strand of human hair was enough to bring about a response, yet sundews, he observed, ignored raindrops.
Darwin understood why the plant did not respond to _______________.
第 4 题
Darwin showed that when one of its leaves snapped shut, it formed itself into a temporary 'stomach', secreting enzymes that could dissolve the prey.
He demonstrated how leaves close and then, for a short period, act like a _______________.
第 5 题
Volkov's experiments reveal that the electric charge travels down fluid-filled tunnels in a leaf, which opens up pores in cell membranes.
The charge enters tunnels, causing _______________ in the cell walls to open.
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