Marriage difficulties adversely affect parent-child communication.
it would be complex sentance
Nixon said that he sold his apartment in New York when he became president in relation to the investigation conducted under his presidency. It is believe that eh gained profit from his public service. This is in defense to his record in the Watergate case.
The correct answer is the last option: If you take away the suffix –n and the prefix un-, the root word is “know”.
Prefixes and suffixes are sets of letters that are added at the beginning (prefix) or end of a word (suffix). They are not words by themselves, but they do change the words' meanings or categories.
In this case, the root is know. The suffix -n is used to change the word's category from verb (know) to noun (known). While, the prefix un- is used to mean NOT. As a result the meaning of the word UNKOWN would be not known or familiar.