评定学生学业成绩的方法有很多，其中学生学业成绩评价的基本方法是______。
参考答案：测验法
As I looked at the memorial, I thought about ____ terrible disaster it was for the people in Nanjing then and ____ they were to fight the Japanese invaders.
A．how, how
B．what a, how
C．what, how
D．how, what
质量为5kg的物体静止在水平桌面上，当受到20N的水平推力作用时恰好开始滑动，物体和桌面的动摩擦因数为0.36．则当水平推力为15N而物体静止时，物体受到的摩擦力大小为______N；当水平推力为40N时，物体受到的摩擦力大小为______N．（g=10m/s2）
