Present主语 was 系动词the usual mix 表语（that so often accumulated into a burden too heavy for a single-parent household like the one Oprah Winfrey grew up in）定语从句.
定语从句中：that 主语so often accumulated into a burden 后面应该是省略先行词的定语从句（which is）too heavy for a single-parent household 后面貌似状语like the one （Oprah Winfrey grew up in）定语
写的乱了点,看得懂不...