"What did you do last weekend?"
If time can be placed at the beginning of the sentence this should be acceptable. But we have to write the way duolingo wants.
Subject comes first! Chinese sentence order is subject + time + place + verb + object. Gets more complicated with particles and measure words but those are the basics.
The two kind of statement should all correct. both saying are common used in China. 上个周末你做什么了？ or 你上个周末做了什么？
no, you can switch between person subject and time subject as you like, it doesn't change the meaning at all.
I don't understand why this is not also acceptable without 了since 上个周末 already specifies the specific time as last weekend.
了 is a completed action marker, and should be used to express past tense.
昨天，上个周末，上周末，already stated the past tense, putting 了 after the verb is valid but it isn't necessary imo.
"le" is used to indicate a completed action or a change in state. Does not necessarily mean past tense though it is often used to represent it.
On the question "what did she do last Tuesday?" 上个星期二她做了什么 was an acceptable answer. On this question 上个周末你做了什么 was not accepted. Is this a mistake?
It's awful!! I'm a Chinese and I've never, I repeat, NEVER seen anyone do that!!
可以的！ 中文的时间状语 通常摆在句首， 或者是 主语的后面。那是更强调时间。 有时时间状语也可以放在后面， 但是中间加上停顿， 如： “你做了什么？ 在上个周末！” 这样的句子更强调你的动作， 而不是时间。 比如说审讯嫌疑犯， “你在现场吗？上个周末！”强调的是 你在不在！ --- 尼尔老爹的评论。 ：） 网站办的很好， 但不是完全正确。
Shouldn't "你上周末做了什么？" be accepted as well? I thought the measure word is optional, like "下周末".
Particles 了 le and 过 guò to indicate past action. I FINALLY found a resource that explained it. - https://www.digmandarin.com/all-video-lessons/grammar-summary-le-chinese and https://www.digmandarin.com/use-le-in-chinese.html
for the guys asking why should we use 了 when 上个周末 already indicated the action happened in the past. imo Adverbs of time don't cancel the verb tense, like in :
(yesterday) I (went) to work we don't say (yesterday) I (go) to work so 了 turns (做/do) to (did)
without 了 it should translate into: what (do) we do last weekend.