What are the problems with my sentences? 她是一个从美国来的姑娘来中国训练中国的足球队。 (是。。的）
一发现她丢了她的题手包就连忙回饭店去，而在饭店里一直搜索总归放弃了。（连忙）
他第一次比赛的时候，虽然在培训他是足球队最好的运动员，但是他居然踢了一脚，没踢足球就不小心地摔倒去了。（居然）


4.作弊，偷了别同学的钱，跷课， 等等，他并不是一个很诚实的人。（并+bu/

5.已经两个星期了，如果作业还没做了你干脆别做吧。（干脆）

6.找房子的时候你总是不满意，不是价格就是风格。（不是。。。就是）

7.一老师告诉我们明天有一个考试大家就不约而同的抱怨了。（不约而同）

8.看他用叉子吃苹果让大家莫名其妙。（莫名其妙）

9.她的父母听到了她没及格了考试的时候不让她一个星期跟朋友们一起出去玩儿所以她费尽心机找办法偷偷的和她的男朋友见面。（费尽心机）

10.她的男朋友跟她分手了但没告诉她原因就让她感觉很困惑。（困惑）

11.那个星期每晚上没睡了五个小时多的觉，她不由得感觉筋疲力尽。（不由得）

Hello, I wrote all these sentences for homework and got a really low grade I was kinda upset about, and I really want to understand grammatically the reason these sentences all have errors. My teacher just circled a lot in red but doesn’t explain how to fix it or why its wrong. If you could help me understand maybe the grammatical structures I’m messing up that would be so helpful for me to improve.

Thanks!
You are asking 11 questions in one post. If I answer all of them, It will be a very long post. Therefore, I would only answer the first question here and please post other questions in individual posts.
&quot;是&quot; is the verb  &quot;is&quot;
One of the functions of &quot;的&quot; is as an possessive marker, adding it after a noun to indicate possessive.
Example: 中国 = China; 中国的 = &quot;China's&quot; or &quot;of China&quot;
Another function of &quot;的&quot; is as an adjective marker. Adding it after any phrase turn it into an adjective phrase
Example:  &quot;从美国来&quot; = &quot;came from America&quot; ;  从美国来的姑娘 = the girl who came from America

&quot;她是一个从美国来的姑娘来中国训练中国的足球队。&quot; is a run-on sentence
&quot;她是一个从美国来的姑娘, 来中国训练中国的足球队&quot;。(&quot;She is the girl who came from America, came to China to train China's football teams&quot;) is the proper form.

&quot;她(是)一个从美国来(的)姑娘&quot; is  a correct answer for the adjective marker function. But your answer didn't use [是 + noun + 的] as a [verb + noun + possessive marker] form. If it was the requirement that you must use this function, your answer would be wrong.
The correct answer should be &quot;这(是)中国(的)足球队&quot; = &quot;This (is) China('s) football team&quot;