The manager, ________ his factory’s products were poor in quality, decided to give his workers further training.
本题考查分词结构作定语。 本句变为定语从句应为“The manager， who knew his factor’s products were poor in quality."”。 The manager 与 know 之间应为主动关系， 定语从句变为短语结构应把动词改为现在分词 knowing。 故选 A。