4.2.2 High Frequency Words
Laviosa（1998）defined“list head”or“high frequency words”as every item which individually accounts for at least 0.10%of the total occurrences ofwords in a corpus.If the sim plification hypothesis is true，there will be a higher proportion of high frequency words in TETT.The statistics of high frequency words are presented in Table 4.5.List head words are displayed in Table 4.6.
Table 4.5 Statistics of High Frequency Words
Figure 4.2 High Frequency Words
The proportion of high frequency words relates to the corpus size.The larger the corpus，the smaller proportion the high frequency words account for.In the one million reference corpus，the high frequency words only account for 43.01%.They make up a larger proportion of the comparable corpus especially in TETT（TETT 48.97%＆OETT 46.41%）.The value calculated by the log-likelihood calculator between OETT and TETT is－41.60，which means they have a significant difference in the high frequency words use（P＜0.001）.The higher repetition in TETT correspondingly means fewer words，which proves the sim plification hypothesis.(https://www.daowen.com)
Table4.6 Top 20 High Frequency Words
Most words in the list head are functional words（grammatical words）.“The”，“of”，“and”appear as Top Three frequency words in all the tourism texts.They are widely and flexibly used in the texts.
High frequency words can be subclassified as determiner（the，a），prepositions（of，in，to，for，by，on，at，with，from），conjunctions（and，as），copulas（is，was，are），abbreviation／genitive（s），pronouns（it，that，you）and nouns.Most of them are functionalwords or“joints”of sentence structure which typify the syntactic features in English.Although the number of functional words is tiny，they are frequently，widely and flexibly used to determine the syntactic structures.Meanwhile，they have various meanings and play an im portant role in cohesion and coherence.
Except for functionalwords，there are a few lexicalwords in the list head.All the lexical keywords are nounswhich elaborate the“field”or contextual settings of texts.Building and city indicate thatmost OETT cultural tourism texts are much related with city；Tem pleproves TETT cultural tourism texts attach much im portance to the religion in history.The difference of“field”depends on the cultural and historical divergence between China and Western countries.The similar discrepancy doesn't exist in natural tourism texts.The difference in“field”between OETT and TETT（Park and island in OETT，mountain and lake in TETT）are geographical but not ideaistic.