Taking a Walk

It was cloudy in this afternoon.

As a result, the temperature was agreeable despite the it being summer.

At this that time the sun had set down and therefore all street lamps turned on.

I walked alone putting with my hands in my pockets.

'I walked alone putting hands in my pockets' gives the impression that you kept putting your hands in and out of your pockets, which is slightly hilarious.

Many students rushed out the teaching buildings and the main streets were flooded in a short time.

'Teaching buildings', wierd expression here. The original sentence in Mandarin please.

Then minutes later, these streets returned to quietness. Then minutes later, the streets were quiet once again.

Now I am involved in a trouble. problem.

I am in a dilemma and hesitate to give make a choice.

It was cloudy this afternoon, so the temperature was pleasant despite it being summer.

No one would say "agreeable" to describe weather. It would seem very out of place to hear that, even though it is grammatically correct. Also, you can combine this sentence with the previous sentence to sound more fluid in your writing.

Since the sun had already set, all the street lamps were on.

The way you said this: "All the street lamps turned on" indicates that the lights turned on while you were walking. The way I rewrite it indicates that the lights were already on before you were walking, and were still on while you were walking. I'm not sure which is more accurate for your story, but I am guessing it's the way I rewrote it.

Occasionally I met some friends on the road.

This sentence tells me that you met friends on the road more than one time. If this is true, then it's fine.

Many students rushed out of the teaching buildings and in a short time the main streets were flooded.

You need the "of" here, but you don't have to move "in a short time". It just sounds better to me.

Then, minutes later, the streets were quiet once again.

Now I have a dilemma and hesitate to make a decision.

I combined this sentence with the previous one to make it more fluid and less repetitive.

After a two and a half hour walk, it began to rain slightly.

At this time, my mood already became better.

My mood had already improved, so I went back to my dorm to write this diary.