As a band instructor at an elementary school, I require my students to turn in practice sheets signed by their parents so I can be sure they are putting in enough time.
作為一個小學的樂隊指揮，為了確保學生投入足夠的時間練習，我要求他們上交由他們父母簽字的練習單。

I had to laugh, however, when one parent wrote on her child's sheet, "Practiced 17 minutes, but it seemed like hours.
可是有一次，一位家長的簽字把我逗樂了。練習單上寫著：“練習了17分鐘，但猶如幾個時辰?！?/div>

【注釋】

(1) band n.樂隊

(2) instructor n.指揮

(3) turn in上交；歸還

(4) signed by their parents:由他們的父母簽名的。這是一個分詞短語作定語修飾sheets.

(5) so I can be sure they are putting in enough time:這樣我才能確定他們投入了足夠的時間。這是so that 引導的目的狀語從句，其中that省略。