At first I thought he was being rude, but I've come to/reached the conclusion that he's just shy.
Dear Jack and Ben: I['ve] been thinking about your last letter for quite a long time and I came to the following conclusion. (Preliminary English Test; B1; Spanish)
In conclusion, I would like to thank our guest speaker for her fascinating talk.
In conclusion, swimming is an enjoyable form of exercise and an excellent way to stay in shape.
In conclusion, music, TV and clothes are very important in a young person's life and can reflect each person's character. (First Certificate in English; B2; Greek)
It’s not fair to jump to conclusions based on one incident.
I think, before jumping to conclusions, we should first try to anal[ys]e the situation. (Certificate of Proficiency in English; C2; Italian)
the dramatic conclusion of the movie
The case should finally be brought to a conclusion this week.
When it comes to the crunch, he is patient and persistent enough to carry a project to a successful conclusion. (Certificate of Proficiency in English; C2; Spanish)
So you thought I was leaving, did you? What led you to that conclusion?
These results lead us to the conclusion that only people with "minds tough enough" will survive. (Certificate of Proficiency in English; C2; Greek)