Like the previous comment said, examples 1 and 3 are correct. In the second sentence, stay is the word you are looking for, not stray. Also, stray can be used as a noun or an adjective to refer to a dog, cat, or other domesticated animal who doesn't have an owner. For example: That cat doesn't seem to have a home so it is probably a stray. The family decided to take in the stray dog.

Number 2

One day I was at home <font style="background-color: yellow;">at</font> 6:30 am, <font style="background-color: yellow;">but</font> I had to go to work at the hospital<font style="background-color: yellow;">.</font>  I turned <font style="background-color: yellow;">on</font> the dishwasher<font style="background-color: yellow;">,</font> and I left my house.
<font style="background-color: yellow;">It</font> was rush hour so there was a lot of traffic. I arrived at 7:30 am<font style="background-color: yellow;">.</font> I opened the door of the hospital, <font style="background-color: yellow;">and</font>  I saw my first patient<font style="background-color: yellow;">.</font> He was a <font style="background-color: yellow;">60-year-old</font> man <font style="background-color: yellow;"> who</font> was a disabled person<font style="background-color: yellow;">.</font> He couldn't walk so he had to use a wheel chair<font style="background-color: yellow;">.</font> Before <font style="background-color: yellow;">attending to</font> him<font style="background-color: yellow;">,</font> a friend of mine asked me "Would you like a coffee<font style="background-color: yellow;">?".</font>  I told him that I <font style="background-color: yellow;">preferred</font> just a bottle of water.
I started to talk with my patient, <font style="background-color: yellow;">and </font>he told me that he had felt very bad<font style="background-color: yellow;">.</font> He had diarrhea and his joints hurt, so I needed to extract blood with a syringe. I extracted blood <font style="background-color: yellow;">from</font> his artery to make an analysis.
After 2 hours I couldn't find a cure<font style="background-color: yellow;">, and</font>  I was so <font style="background-color: yellow;">frustrated</font> that I didn't want to talk<font style="background-color: yellow;">.</font>  I went<font style="background-color: yellow;"> to look</font> for help, but when I left the room a nurse spilled her coffee on my shirt<font style="background-color: yellow;">.</font> I felt very angry<font style="background-color: yellow;">,</font> but I just Ignored it and<font style="background-color: yellow;"> left to find</font> help<font style="background-color: yellow;">.</font> When <font style="background-color: yellow;">we</font> came back<font style="background-color: yellow;">,</font> the <font style="background-color: yellow;">man</font> told us that he felt better and he wanted to go home<font style="background-color: yellow;">.</font><font style="background-color: yellow;"> We</font> read his analysis and everything <font style="background-color: yellow;">seemed to be</font> fine, so we let him go.

I hope this helps. 

It depends on the context, but it probably means that it's an indisputable success or a total success. In other words, it's not a partial or conditional success.