第一个错误：He has mathematical achievements _that_(去掉) about five geometric theorems:
第二个错误：(4)that the angles inscribled inside a semicircle__is__（are） a right angle,
第三个：(5)that a triangle is determined if its base and the(去掉) two angles at the base are given.
第四个;His mathematical achievements are difficult to assess because no writings by Thales survive(d),and no contemporary sources exist.
第五个：He also believes（believed） that the entire universe was （is）a living organism, nourished by exhalations from water. He trys（tried） to explain nature by nature itself (not by God).