Answer:
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.'
Is this a question???????
Usually, in a conclusion, you wrap up what you have been writing about the whole time. So, a conclusion is basically a summary of the whole text. You can introduce new ideas for the reader, but it is usually inadvisable. In a couple of sentences, you should finish your text, referring to the previous paragraphs and just wrap it all up nicely.
The correct plural form of echo is echos or echoes. Either way it is grammarly correct. I believe that echoes is the correct form.
echoes
