5.2.2 Coherence
As for coherence，it refers to the semantic relationship between the sentenceswithin a text，especially those which represent propositions or communicative acts.As van Dijk（1977：93）pointed out，“intuitively，coherence is a semantic property of discourses，based on the interpretation of each individual sentence relative to the interpretation of other sentences”.If cohesion can be taken as a micro point of view，coherence can be understood as a macro one.
To make different parts of the text stick together，there need linking words and linking phrases，or discourse markers.Schiffrin suggests paralinguistic features and non-verbal gestures are possible DMs（Schiffrin 1987：315）.Her interest is the ways in which DMs function to“add to discourse coherence”（Schiffrin 1987：326）.Redeker who calls DMs discourse operator suggests that“the core meaning should specify themarker's intrinsic contribution to the semantic representation that will constrain the contextual interpretation of the utterance”（Redeker 1991：1164）.Fraser understands DM with a grammaticalpragmatic perspective.He pointed out DMs“cannot introduce a sentence which stands alone，but requires that the previous independent clause be present”（Fraser1999）.Blakemore（2002：32）believed DMs have only a proceduralmeaning，or non-truth conditionalmeaning.To sum up the above arguments，DMs have no effect on the conceptual meaning but help to shape“context of situation”.According to Fraser，there are three types of DMs：contrastive markers，elaborative markers and inferentialmarkers.Each type is counted as follow s：
Table 5.2 Statistics of Discourse Markers
The details of contrastive markers are as follow s：but（99／50），still（56／21），though／although（42／25），however（40／28），instead（2／2），despite（6／1），in contrast（2／1），nonetheless（2／0），rather than（1／2），on the other hand（1／0），in com parison（1／0），in spite of（0／1）.Specifically，elaborative markers include and（567／641），also（148／107），or（12／9），aswell（11／2），yet（4／4），too（1／4），in addition（0／9），otherwise（2／0），namely（1／0），likewise（0／3），moreover（0／2），furthermore（0／1）and besides（0／1）.Inferential markers comprise so（30／25），then（18／12），because（14／22），therefore（2／18），hence（2／12），of course（2／1），as a result（1／0）and for this／that reason（0／1）.For all the statistics above，the former refers to the frequency in OETT and the latter refers to the frequency in TETT.
As a whole，there is no significant difference in total hits of discourse markers between OETT and TETT.However，different kinds of markers vary much in details.As themost extensively distributed ones，the elaborativemarkers proportion closely in OETT as in TETT（OETT 746 hits，1.24%＆TETT 783 hits，1.30%），disposing a tiny discrepancy（LL，－0.87）.The statistics is sufficient to prove the functional importance of elaborative markers in discourse.Actually，the additional information in the discourse relies on elaborative markers to offer.Contrastive markers（especially but，still，though／although，however）and inferentialmarkers（especially therefore，hence），however，manifest great difference in OETT and TETT（LL38.99，－8.53）.
Exam ple 21：(https://www.daowen.com)
（1）Just considering the weather，the cooler dry season from April to October is the best time to visit Bali.The rest of the year is more humid，cloudier and hasmore rainstorms，［given information］but you can still enjoy a holiday［newinformation］.（OETT）
（2）Visiting the ice cap is possible from most towns in Greenland［given information］，although it usually takes a helicopter flight or a boat trip to reach the edge of the inland ice［newinformation］.In Kangerlussuaq the ice cap is only 20 kilometers away and you can hike，drive，fly ormountain bike to there—and stay overnight if you bring a tent.（OETT）
（3）For Americans over 30，these magnificent Victorian homes are easily recognizable from the openingmoments of the 1990s sitcom，Full House［given information］.For other visitors，however，they are simply recognized as exquisite homes painted in colorful hues，incredibly well-preserved and a joy to view［newinformation］.（OETT）
（4）Spring comes in April but its onset is delayed by three days for every 100 meters as you climb them ountain［cause］.Therefore，when wild flowers are brilliant and seedlings are shooting up at its foot，the plants halfway up themountain will be justawakening from theirwinter sleep and will not exhibit their beauty until a week later［effect］.（TETT）
（5）The gentle water turbulentand gains speed as it rushed forward till it finally cascades over the waterfall，forming an illusion of water being poured from a kettle［cause］，hence its name“Hukou or Kettle spout”［effect］.（TETT）
Besides elaborative markers，OETT tends to use contrastive markers to narrate.TETT，however，tends to use inferentialmarkers to narrate.In OETT，the given information and the newinformation are made a strong contrast with each other.The concession patterns create vivid im pression to readers.In TETT，however，the given information and the newinformation are often presented as cause-effect patterns which lead to plain narration.This pattern is influenced by Chinese original texts where inductive reasoning is popular.