Could someone explain why helfen takes a dative object? Or is it just something one has to memorize?
cough ... "dem Mann" is dative, not accusative. And that's used because "helfen" takes a dative object.
Someone please explain! Jemand erklären sie bitte!
My result on duolingo is 68% advance and I have studied all the topics. How can I have 100% ? Since no more new topics are there, Do I have to keep practicing daily? If this is based on making more XPs, then how many more XPs I need to make it daily?
Duo never goes above a certain percentage fluency, because they realize that 100% fluency cannot be achieve without actually speaking the language in real time. Different languages seem to have different top %. I think 68% is as high as it goes in German--perhaps 70% I've been at 67% for the better part of a year. My tree is almost always clear.
Not in English :}
"This is the man, to whom I extended help" would work.
"..., whom I helped" would work too. That is, drop the unnecessary "to". Even better "..., whom I have helped". The latter is right in sync grammatically with the German one.
Why even have das Wort "habe" in das Satz?
Could one do without it? How does it change the translation?
"Habe" is necessary. Leaving it off would be like saying "That is the window I broken" instead of "have broken" or "broke." The relative clause needs a verb, and "habe" is it.
I am an English speaker and I don't think I have ever said the word 'whom' out loud. That being said, I was probably say 'that is the man that I helped' or 'That is the man who I helped'