Causal Question Answering

My recent task on causal question answering . Causal Question Answering means there should be a causation relationship between question and answering , such as He died of cancer . Question : why did he die ?
Earthquake generates tremor .
Question : Why is tremor generated ?

Another part of it is causal Relation Extraction : you have to extract causal relation from a sentence . Causal Relation means there should be cause effect relationship in the sentence . Such as I canot go out as it is raining . Here effect is "I canot go out " cause is " it is raining " . Here as is a relator . Relator means which connect cause and effect . SOme of the relators are since , after , as , before .