Solution: Solution: A. As shown in the figure, at t 1, the tangent of point A on the solid line is AB, and its slope is equal to the actual acceleration. As can be seen from the figure, the acceleration reflected by the dotted line is less than the actual acceleration, so A is wrong;

B. In the v-t image, the displacement is equal to the "area" surrounded by the corresponding graphic line and coordinate axis. In the time of 0 ~ t 1, the displacement corresponding to the dotted line is greater than that corresponding to the solid line. From V=st, the average speed calculated by the dotted line is greater than the actual speed. Therefore, B is correct;

During the period of C.T 1 ~ T2, the dotted line reflects the uniformly accelerated linear motion, so c is wrong;

The dotted line in D, T3 ~ T4 is a straight line parallel to the time axis, and the movement reflected by this line is a straight line with uniform speed, so D is wrong;

Therefore, choose: B.