“There was a plate that recommended to be cautious because it was the season when some of the animals were dangerous.” Plate would be unusual here and I think this may be a typo. Do you mean to say “ There was a place that recommended caution because... I think the rest of your sentences are quite understandable. In 5 it would be okay to use barged for swept if you want to convey rude behavior.

1) There were two prospective candidates on this post. Nearly: There were two prospective candidates for the post. 2) Many people in the audience changed their perspective after his presentation. Good 3) If you want your house to stand for a long time, you have to build a firm foundation. Yes however could be summed up much shorter: If you want a house to last, you must build on solid foundations. 4) There was a plate that recommended to be cautious because it was the season when some of the animals were dangerous. Not quite: A sign warned people to be cautious, advising that it was the season where some animals may be dangerous. 5) He swept through the waiting room without paying any attention to other visitors. Fine

4) There was a sign that recommended to be cautious, because it was the season when some of the animals were dangerous. The only things I would have changed otherwise are purely stylistic. Nice work!

Thanks!)

1. correct 2. correct 3. correct 4. correct, but it would be a bit simpler for spoken english (complicated sentence) - maybe “there was a plate/sign that recommended to be cautious because this season the animals are dangerous” 5. correct but “swept” usually refers to eyes- so if it’s talking about what he sees it would be “his eyes swept through the waiting room” and if it’s him walking and moving then “he walked/moved through the waiting room"