In Greek, we need two words. "σε" is a sort of an all-purpose preposition used in place of many English prepositions.
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And never trust dictionary translations of sentences...they are more often wrong than right.
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You asked above why English only had one word to express "near" and I told you Greek needed two words.
"σε" is the prepostion used with "κοντά". As you you would say in English for example...I'm sitting "at" the table. Why do you us "at" and not "on" or "in" or "under"? The preposition "at" gives you the picture of where I'm sitting. SEE you use prepostions all the time in English.
Ο = the αντρας = man ειναι = is κοντα σε = near μια = a γατα = cat
Please reread what I wrote...It's prepositions = https://www.lexilogos.com/english/greek_dictionary.htm
Your best bet is to use the Drop Down hints to do the translations and not try to figure out every tidbit of grammar.
The Duolingo method is to have you learn how to express things in the new language.
And this is very important this question has already been asked and answered twice on this page.
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Some simple hints to get you started:
1 Always read the comments before posting.
2 Read the Tips & notes, on the first page of each lesson you’ll see an TIPS. Click on that.
3 Read the drop-down hints. Pass your cursor over a word and a list of words will appear. The top word/phrase is usually the best choice. Or go to the top of the page and click MORE you’ll see a dictionary; just type the word.
4 Use the Report options at the foot of the exercise page to Report issues such as **My answer should be accepted.” etc Then be sure to leave a comment on the Discuss Forum
These are the official Duolingo guidelines which you should read.c.
https://www.duolingo.com/guidelines And these will answer lots of questions about how Duo works.
"close to" is also one of the accepted translations. Therefore, if your sentence was not accepted there was an error in another area. We moderators cannot see your sentence therefore before you posted your comment here you should have made a REPORT.
Here's how to report.
Go to the bottom of the exercise page where you'll see REPORT Click on that:
Then choose what you want to REPORT: (You'll see these to choose from.)
-The audio does not sound correct.
-The dictionary hints on hover are wrong or missing.
-The Greek sentence is unnatural or has an error.
-The "Correct solution" is unnatural or has an error.
-My answer should be accepted. This is the one you should click on if your translation was not accepted.
After choosing the REPORT you want to make you should post on the comment page.