You are given an English sentence with a blank, and you need to predict the missing word. After completing, the whole sentence should be gramatically correct and non-ambiguous.
One example: The kid on the street is ____ soccer
Solution is here: playing
Explanation: This is the original sentence 'The kid on the street is playing soccer' So, we have correctly predicted the missing word to be 'soccer'

Now, solve this: and the conversation which had become interesting during the discussion of ____ serious affairs
Solution:
such