事
こと
after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to
よくある事 is read as よくあること (yokuarukoto) and means common occurrence.
よくあること
yokuarukoto
こと
after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to
よくある事だが、トムは授業に遅刻した。
Tom was late for class, as is often the case.