喇叭里响起“我和你,心连心…”的歌声,小凡说:“是刘欢在演唱.”他的判断是根据声音的( )
下列句子中“之”的用法(意义)与例句相同的一项是( )
例句:居庙堂之高,则忧其民
— Four students in Qingdao stood in line against a man to save a woman teacher at the school gate.
— _________ great courage they had!
方程x-12=x-1的根是( )