-- Look! The man is __________ the poster at the bus stop.
-- Let's go and stop him. We should keep our city clean.
读材料,回答问题。
子(孔子)曰:管仲相桓公,霸诸侯,一匡天下,民到于今受其赐。
子又曰:桓公九合诸侯(多次召集诸侯会盟),不以兵车,管仲之力也。
若a为实数且(2+ai)(a﹣2i)=8,则a=( )