(1) (1) In the experiment, the slight inclination of the board is to balance the friction. The purpose is to make the tension of the rubber band on the car equal to the resultant force, that is to say, the work done by the rubber band is equal to the work done by the resultant force on the car, so C is right, and the car can move at a uniform speed after the rubber band is relaxed, so D is right, and obviously A and B are wrong.

② The trolley speed is V = (4.00+4.00) × 0.012× 0.02m/s = 2m/s..

③ According to the knowledge of mathematical function, the graph line may be a parabola (quadratic function) or a cubic function, but it cannot be a hyperbola or a square root curve, so the error CD of AB is correct, so the guess is definitely incorrect.

(2) (1) Because the current flowing through the small bulb is required to be adjusted from zero, the sliding rheostat should be connected in partial pressure. Because the internal resistance of ammeter can be ignored, ammeter should be connected internally. The circuit diagram is shown in the figure, and the physical connection diagram is shown in the figure below.

② As can be seen from the I-U diagram, when I=0.4A and U=6.0V, the power of the small bulb is P=UI=6.0×0.4W=2.4W?

So the answers are (1) 1cd, 22, 3ab.

? (2)① As shown in the figure, ②6.0, ② 2.4.