Prepositions are an important part of grammar.

I placed the materials before the important meeting.

His success happened right before my eyes.

I forgot to do the pre-pasting, so I will do it now.

He studied all night on the eve of the exam.

He made some preliminary statements before getting to the main topic.

Please submit this report in advance.

The sumo wrestler ties his mawashi (the front part of the belt) tightly before the match.

This rain is a harbinger of the typhoon.

The recipe was published in the previous issue of the magazine.