A. When the system is initially in a stationary state, the elastic force of the spring is equal to the component force of A's gravity along the incline. When B just leaves C, the elastic force of the spring is equal to the component force of B's ??gravity along the incline. Therefore m2gsinθ=kx2, x2 is the elongation of the spring relative to the original length, but since the spring is compressed at the beginning, d>x2, so m2gsinθ>kd, so A is wrong;
B, when B When it just leaves C, the elastic force of the spring is equal to the component of B's ??gravity along the inclined plane, so m2gsinθ=kx2. According to Newton's second law: F-m1gsinθ-kx2=ma, it is known that m1gsinθ=kx1, x1 x2=d Old thing The acceleration of block A is equal to F?kdm1, so B is correct;
C. The instantaneous power of the pulling force P=Fv, so C is wrong;
D. According to the functional relationship, the elastic potential energy of the spring The increase is equal to the work of pulling force minus the increase in kinetic energy of the system and gravitational potential energy, which is:
Fd-m1gdsinθ-12m1v2, so D is correct;
So choose: BD.