5. He had no idea that learning phrasal verbs would be so difficult. did he know that phrasal verbs would be so difficult to learn.
• Little
• When
• Only
• Less

When did he know that phrasal verbs would be so difficult to learn.

Adjective clauses  begin with words such as that, when, where, who, whom, whose, which, and why. an essential (or restrictive)  adjective clauseprovides information that is necessary for identifying the word it modifies. so for example*** wrong= i the man gave me direction. example right ( i the man who gave me the  direction.