1.tell him that he can do it well.
2. He thinks that you can do it. (명사절 접속사)
3. you feel like that you should act like a teacher.
4. He never says that it is difficult.( 명사절-목적어절을 이끄는 접속사)-2번과 동일 역할 ..

맞나요? 1번 3번 궁금해요.