人体神经调节的基本方式是[ ]
A．反射
B．反射弧
C．条件反射
D．非条件反射
答案：A
She is a good student. She always finishes _______ her homework on time. [ ]
A. do
B. to do
C. doing
D. to doing
如图所示，斜面倾角为37°，当斜面体沿水平面以9m/s2的加速度运动时，置于斜面体斜面上的质量为2kg的木块刚好不上滑，则木块受到的摩擦力大小为多少？（sin37°=0.6，cos37°=0.8，g=10m/s2）
