Im a beginner too, but wanted to say even though the last one is underexposed, I love it. I have a similar picture looking over the brooklyn bridge. It was taken over 8 years ago, but its still one of my favorites. Good start!
1. Whether by accident or design, you've captured an image which could be used ina text-book on composition. The trees and benches work to form leading lines which direct the viewer's eye to the couple, the bright spot in front of the holds the eye, nd the vaguely heart-shaped branches give it a romantic aspect. The monochrome conversion is nicely done as well. About the only suggestion I have here is that I think cropping a bit off of the bottom so that the bench 'starts in the lower, RH corner might make it even stronger.
2. It's a flower with a honey bee. Not the most exciting, but it is well focused and exposed. Remember when shooting tall, narrow subjects (people, flowers, buildings) that a vertical or portrait orientation works well; not the tips of the petals you've cropped at the top.
3. This image needs to be leveled; the horizon goes down drastically to the right. I would also crop some off of the LH side, just to remove that island/bit of land middle-left.