The article gave the impression that the teachers were above reproach.

reproach 是名词，意思是"责备、指责"，来自动词 reproach（责备、批评）。 above reproach 是一个固定短语，字面意思是"在责备之上"，引申为"无可指责的、无可挑剔的"，表示某人或某事完美无缺，找不到可以批评的地方。