In this task, you are given two sentences in the English language and your task is to classify them into one of their discourse types. A discourse type is an indicator to classify the given two sentences on the basis of a co-text as well as a relevant context. There are 13 discourse types in total which are 'SINGLE_S_COORD', 'SINGLE_CATAPHORA', 'SINGLE_CONN_INNER', 'SINGLE_APPOSITION', 'SINGLE_VP_COORD', 'SINGLE_CONN_START', 'PAIR_ANAPHORA', 'PAIR_CONN', 'SINGLE_RELATIVE', 'SINGLE_CONN_INNER_ANAPHORA', 'SINGLE_S_COORD_ANAPHORA', 'PAIR_CONN_ANAPHORA' and 'PAIR_NONE'.

Sentence 1:Visiting Tom 's grave , Alice finds a note left by Doug which reveals the killer to be Alice 's friend Marlena Evans . Sentence 2:nan
SINGLE_CATAPHORA

Sentence 1:In Saccharomyces cerevisiae ( Baker 's yeast ) , the transcriptional regulation of the INO1 gene encoding inositol - 3 - phosphate synthase has been studied in detail and its expression is sensitive to the availability of phospholipid precursors as well as growth phase . Sentence 2:nan
SINGLE_S_COORD_ANAPHORA

Sentence 1:The seventh wall contained the Citadel with the white Tower of Ecthelion , which was 300 ft ( 91 m ) high , so that its pinnacle was one thousand feet ( 300 m ) above the plain . Sentence 2:nan

SINGLE_RELATIVE