Where is your sister? She _____in the study.( )
A:is
B:am
C:are
韩非在批评某家学说时说:“举先王,言仁义者盈廷,而政不免于乱。”他批评的是
(Ⅱ)已知a2+b2+c2﹣2a﹣2b﹣2c=0,求证: 2a−b−c≤32 .