How to Use Query Builder in complicated SQL?

Need Help
1

I just started CakePHP3 and need help.
Im trying to create above query by using Query Builder .
but i can’t find out how to make left join part.

select *
from Users
Inner join Comments on Users.id = Comments.user_id
Left join (seledt avg(score) AS AVG_SCORE from Comments_Score on Comments.id = Comments_Score.comment_id)
Order BY AVG_SCORE DESC

PLZ help.