B, the force analysis of the object P shows that gravity and tension are balanced, so the tension of the rope is equal to the gravity of the object P; When Q is pushed horizontally to the left, P and Q are still motionless, so the tension of the rope is still equal to the gravity of the object P, and the tension on the light rope must remain unchanged; So, B is wrong;

A, then analyze the force on the object Q, which may generate static friction due to gravity, tension and support;

When the static friction is upward along the inclined plane, there is t+f = mgsinθ; When the q level is pushed to the left, there is t+f+fcos θ = mgsinθ; The static friction force F will decrease, or the friction force may decrease first and then increase reversely;

When the static friction is downward along the inclined plane, there is t = f+mgsinθ; When the q level is pushed to the left, there is t+fcos θ = f+mgsinθ; Static friction will increase; So, A is wrong;

The pressure between c and q on the inclined plane is equal to the sum of the vertical component of gravity and the vertical component of thrust, so it must become larger, so c is correct;

D, finally analyze the overall stress. At first, these two forces were balanced by gravity and support; After the thrust to the left is applied, the whole body is subjected to static friction to the right; Therefore, the friction between the inclined plane and the ground is bound to increase; Therefore, d is correct;

So: CD.