如图所示,已知P是正方形ABCD外一点,且PA=3,PB=4,则PC的最大值是____
“天苍苍,野茫茫,风吹草低见牛羊”描写的是 牧区的景观( )
5÷9=0.56
18+58 =____ 310+1310 = ____ 2312−1312 =____
16+136 = ____ 149−89 =____ 34−14 =____