I love all the images your posts, but you should consider reading the Steemit FAQ about Plagiarism, Spam, and Abuse ( esp. https://steemit.com/faq.html#Is_it_okay_to_use_random_pictures_from_the_internet ) and at least name the !sources of photos in your posts before you get downvoted.

But on Steemit Faq says is ok to use pictures from Pexels or Pixabay ... and from the mode they wrote no attribution is required... And why to make attribution to a site that actually is not the copyright holder of that pictures... some pictures don't even have copyright holders as they were released to public domain as I understand...

Of course it's OK, but this way you pretend they are your photos. It would only be fair, even if the photos are CC0 licensed. Link tothe original author's portfolio page at Pexels or Pixabay or wherever. I also have photos on several CC0 sites and sometimes I even get paid by users and many times I get a "thank you" etc and this makes me happy, like all other authors and photographers out there.
Of course we are giving the photos away for free with CC0 license, but we are doing this with the intention to be noticed by others ... what you are doing is to go to Pixabay, look for a nice picture, copy it and add a few words to pretend you are what you are not.
And you may of course carry on doing what you are doing since CC0 is CC0...
So, to bring it to an end: Honesty and fairness are very important here.

Just linking to the site isn't enough?? Or just tell the site as source but without linking..?

You do what you do - at the moment you are only posting images from other people and pretend they are yours - when the image is linked your visitors still don't know more.
CC0 images do not need attribution, that's right. What would you think: You have made a nice photo and put it to your portfolio of CC0 images on Pexels. Then someone downloads the image, shows it on his blog and earns money with it ... what would you think?

I can not teach you honesty, I cannot teach you fairness.
I am just a little Steemit member and my intention is to provide my best own work and when I use someone else's work I will say "thank you" and tell everybody his or her name.

Just posting an image without attribution doesn't mean we pretend to be ours... revise your logic a bit ...

What do you believe, what people will think whose image it is when they see your post?
At least I have tried - please don't reply anymore!

When posting content that either is owned by someone else or inspired by someone else’s works, it is proper to list the said source in your post with a link to the original.

Failing to do so is considered plagiarism, and could result in being blacklisted by curation groups or even flagged.

Examples include:

• Using another artist's original drawing/painting/digital art as a “study” or inspiration without linking the original and giving credit to the original artist.
• Linking to someone else’s YouTube video with no source.
• Using someone else’s photos or text without linking to the original source etc.

Please make sure you do so in the future, thank you.