A:to hit
B:hits
C:hit
—Where is Lucy? I can't find her now.
—She ___________ Shanghai on business. She ___________ back in three days.
用简便方法计算下面图形的周长.
____
设 a,b,c 为不全相等的正数,且 abc=1 ,求证:1a+1b+1c>a+b+c .