如图，菱形ABCD中，对角线AC、BD相交于点O，不添加任何辅助线，请添加一个条件 ____，使四边形ABCD是正方形（填一个即可）．

    My feelings about science have ____(complete) changed. More than one science teachers at my new school____ excellent and____(friend). The science____(facility) are very good with laboratories that have all the____(late) equipment. Our chemistry teacher takes us to public science lectures about four times____ term，____are always interesting, because the lecturers are famous at their area of science. In the last 20 years, seven Canadian scientists____(win) the Nobel Prize. Now____I'm becoming more and more interested in is physics and I want to study it at university. But my parents are____(astonish), as they always thought I would become an English teacher.