Welcome to the forums! these are some good practices but you may want to not upload a whole lot of images in one post because it makes it harder for people to give feedback to a specific image. I usually do 4-5 images at the most.
on the first and fith image you can extend you line of action past the torso and connect it to the leg if it follows the same flow like for example in the fifth image the person on roller skates you can make the line of action a lot longer connecting it to the leg in the foreground. same goes for the first image pose on the far right but only up to the where the knee ends
on the second image the pose on the bottom right you should be careful to look at where the ribcage and pelvis are because in yours the pose is straight up and down while the ref has the pelvis shifted to the right making the circles smaller than what you drew especially the pelvis circle
the second body proportions you could probably not make the inside of the males lower legs as curved as you have it and in the first proportions the the woman lower leg and ankles look too thin
your gesture is coming along nicely and your cylinders and cross contours when breaking down poses are on point. your perspective romms look awesome as well. the last thing I will say is that you last proportion study at the bottom the female's breast are too far apart and they should come together closer to the middle of the chest. You'll also want to shift the eyes to the center of the circle and make the nose bigger for both faces because there is too much space for the forehead
Great practice overall keep up the good work and can't wait to see where this course takes you on your art journey. 
