1). Literature <u>can be classified</u> into four main kinds.
2). The institute supported his efforts in the search for a <u>problem</u>.
Explanation:
The first sentence has been converted into the passive voice by substituting the subject 'we' with the object 'Literature' in order to shift the emphasis from the former to the latter and the verb. The antonym of 'solution' i.e. 'problem' has been employed in the second sentence as per the requirement. It means straightly the opposite of the 'problem.'
