问答题
1 It is generally agreed that people read to understand the meaning of the text. 2 However, there are 3 different models proposed about how readers actually arrived at the meaning. 3 Here is the "Bottom Up" model which proposed that readers build up the meaning of the text letter by letter, word by word, sentence by sentence. 4 Until one level of processing has finished the next cannot begin. 5 They build up the meaning of the parts of the text and in this way eventually arrive at the meaning of the whole.
（5）处填入（）直到过程中的一个水平(阶段)完成，下一个阶段才能开始。