Writing concise sentences

His behaviour is going to deteriorate throughout the story.

In the case of the narrator in the story

Due to the fact that I have a meeting at 3 pm in the afternoon, I must depart from my current location prior to the time that the clock strikes 2:30 pm.

At this point in time, it is my honest opinion that the situation we are currently facing is one that requires a significant amount of attention and careful consideration on our part.

It is important to note that, in my personal opinion, the movie we watched last night was rather disappointing.

There is no doubt that she will definitely be able to complete the task successfully, given her level of experience and skill.

In my opinion, based on my personal experience, I firmly believe that the novel we read in class was incredibly interesting.

Due to the fact that it was raining heavily outside, we decided to stay indoors and watch a movie instead of going out to the park like we had originally planned.

The primary reason for his decision to decline the job offer was the fact that the salary was not high enough to meet his expectations.