3. Two squares with side lengths of 1 and 2 respectively, one of which is on the same horizontal line, and the small square passes through the big square at a uniform speed from left to right along the horizontal line. Let the passage time be t, and the area of the big square except the small square is s (shaded part). The approximate image of s changing with t is as follows.

A B C D

4. It is known that in the direct proportional function y = kx (k ≠ 0), y increases with the increase of x, and in the inverse proportional functions y =-y 1), (2, y2) and (3, y3), the relationship between y 1, y2 and y3 is

K intersection (3, xa.y1< y2 < y3b.y1> y2 > y3c.y1> y3 > y2d.y3 > y1> y2.