题干
—Tom, your books should be in right order.
—OK. I’ll ______ right now.
—OK. I’ll ______ right now.
A：put them dow
B：put them away
C：put them u
D：put them o
答案(点此获取答案解析）
B
，AC=2，若O是△ABC内部一点，且满足
，则
等于（ ）