The sentence is I believe it is unpleasant and inconvenient that trash bags are building up on our streets, especially because they are starting to stink due to the extreme heat.
What is a formal letter?
Formal letters are written for official purpose, especially when the person doesn't know about the topic or content.
Formal letters should be written in a gentle tone.
You also make an effort to write as simply and plainly as possible, and to keep the letter to a minimum.
Remember to avoid using informal language such as contractions.
Thus, the gentle form is I believe it is unpleasant and inconvenient that trash bags are building up on our streets, especially because they are starting to stink due to the extreme heat.
Learn more about formal letters.
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