it was ---he came back from Africa that year ---he

not until……that……是高中阶段的固定句式,记住就可以了,not till其实也有,只是高中题目中几乎不出现,出现一般也不是正确答案,如果要说区别,until一般指某件事在特定的某件事已经发生之后,而till一般指这件事还没发生,举个例子：
I will sleep till midnight.正确
I will sleep until midnight.错误
I will not do that until this is done.正确
I will not do that til this is done.错误
一般出现not,都会用until