We tested whether the proportion of typical sentences in a series of auditory sentences would lead people to adjust the strength of activation of world knowledge (i.e., retrieval rules adaptation) during comprehension. This issue is important because it could help clarify how people efficiently integrate different memory information in cognitive processes. In two experiments, all task materials were presented to participants as a whole package, in which proportions of typical sentences, with typical final locations, varied under different conditions. In Experiment 1, the proportion of typical sentences was equal to the atypical ones (i.e., 50% typical vs. 50% atypical), whereas in Experiment 2, the proportion of typical sentences was not equal to the atypical ones (i.e., 75% typical vs. 25% atypical, and 25% typical vs. 75% atypical). Visual fixation on the critical area in a visual display before/while hearing the critical words was compared across conditions, and across-condition differences were used as an index of the adaptation of the retrieval rule in the activation of world knowledge. The findings indicated that the adaptation of retrieval rules occurs throughout the whole test package of sentence comprehension, and the strength of activation of world knowledge in sentence comprehension can be adjusted.