句意：如果不解決,這個問題可能導致更加困難的局面.
補充完整：
The problem may lead to a more difficult situation if it was left unsloved.
leave sth.+ adj.使.處于某種狀態(tài)
狀語從句中,如果從句主語和主句主語一致,從句中又有be動詞,從句主語和be動詞可以被省略.
例如
Look when crossing the street.(=Look when you are crossing the street)