help的形容词是？

　　It is often helpful for teachers to shadow managers in industry.

　　教师跟随业界的管理人员实地学习，常常会很有收获。

　　I called the police but they weren't very helpful.

　　我叫了警察，但他们不太肯帮忙。

　　You'll find it helpful to talk things over with a friend.

　　把情况和朋友详细聊一聊，你会觉得大有帮助。

　　The people I spoke to were very helpful.

　　我交谈过的人都很肯帮忙。