阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。
People feel _______(puzzle) by some unexplained phenomena, one example of      is the possible existence of Yeti.      is said that the Yeti is______(tall) than an average human but walks with amazing speed and strengths. Though some people even reported________(see) the footprints belonging to a Yeti, no stronger evidence for its _______(exist) has been found.
_____the development of science and technology, ______ is unknown to us today ______(be) explained in the future. We hope that ________(science) will solve the mystery one day and give us a satisfactory answer.