知识加油站 先锋 him an some pe nc ils ， an d a drawingbo tu res ， o k B ， dhebegan w ereen drawingpic go w too ． ut t hey nevero d ． Wh m Billy e as if a an ve y earso ar ldd e ， ， his e ot he r gav o him a an sm llblackbo eraser ． som 固 pieces f c halkdHhked 警龠
