Questions about example sentences with, and the definition and usage of "Duolingo"

A: It means "close by" in Spanish it would be "la tienda está más adelante"

A: 😅
壊れているので、母はドアを修理しています。
母は、壊れているのでドアを修理しています。
確かに、どちらも日本人からしたらちょっと変な順番ですね。

Duolingo のこの質問を作っている人もBilingual で、実は日本語の方が第2母国語の可能性は十分ありますよ。正解の日本語は1番直訳に近いですね。その人なりのこだわり、理解があっての上の正解なのでしょう。他のappでも、これちがうじゃんということはよくあります。
あまりこだわらずに「違うんじゃん？」くらいで次に行くのをお勧めします。😅

A: Most native English speakers don't know the difference between "who" and "whom," and for that reason, most of the people I know would say "who is this email for," but "whom" is grammatically correct.

A: "Could" implies there's some sort of context, like you and your friend were in a situation where you needed to speak Chinese and they were there to help you out.
"Can" gives a more general feeling, like in general it's good that your friend can speak Chinese.
Looking at the Chinese sentence, and just guessing there isn't much context, I'm assuming Duolingo was looking for the second.

A: You’re asking in the english section

A: × Duolingo can be helpful in the begin, but when you get in intermediate it gets to being boring, i agree with you about the fact it has superficial phrases, but you can get a good vocabulary there
✓ Duolingo can be helpful in the beginning, but when you get to an intermediate level it starts to get boring. I agree with you that it has superficial phrases, but you can get a good vocabulary there.

well done!