水滴自屋檐由静止落下，经过高为1.8米的窗口历时0.2秒，若空气阻力不计，屋檐离窗顶多高？（g=10m/s2）
3.2m
The selfless village doctor treated any poor patient who came to his house without any ________.[ ]
A．cost
B．payment
C．charge
D．price
函数f（x）=2|x|的最小值为______；图象的对称轴方程为______．
