On March 14, maths and science lovers around the world celebrated a special day: Pi Day.

    Pi is____ to3. 14, but the number goes on endlessly. It is sometimes written in Greek,π. With the help of computers, mathematicians have been able to ____ pi out to over trillion (万亿) decimal places, but there is still no____ to the number. This makes pi puzzling, even for the most famous scientists and mathematicians.

    Pi Day is celebrated around the world on March 14, since how we write this date, 3/14,looks just like the number pi.

    For some people, the appeal (吸引力) of Pi Day goes far beyond maths and science. Pi shows up____popular culture. You can see it in movies, comics, music and more. "In modern movies, any time the filmmaker wants to evoke (产生) a sense of mystery, often the symbol pi is used, "says David Blatner, Jewish American writer of The Joy of Pi.

2008年，中国首次举办奥运会，之前已向全世界发布了本届奥运会会徽，它由“京”这个汉字组成。我国最早实现文字的统一是在（  ）

若菱形ABCD的周长为8，对角线AC=2，则∠ABC的度数是（ ）

2012年8月30日，东盟与其6个自由贸易伙伴（澳大利亚、中国、印度、日本、韩国、新加坡）经贸部长会议在柬埔寨举行。下列东盟成员国中，与我国陆上相邻的是(    )。

地里庄稼出现叶黄、株矮、生长迟缓等症状，需施加复合肥。下列物质属于复合肥的是(  )