TASK DEFINITION: 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'.
PROBLEM: Sentence 1:Although still an island by name , Deer Island has been connected to the mainland since the former Shirley Gut channel , which once separated the island from the town of Winthrop , was filled in by the 1938 New England hurricane . Sentence 2:nan

SOLUTION: SINGLE_CONN_START

PROBLEM: Sentence 1:Although the cabin lights remained lit , they were at first unable to find the astronauts through the dense smoke . Sentence 2:nan

SOLUTION: SINGLE_CONN_START

PROBLEM: Sentence 1:Ray Vargas , a witness to the lights on February 17 , believed he witnessed something extraordinary . Sentence 2:nan

SOLUTION:
SINGLE_APPOSITION