采用本次课程中学到的be of......的使用方法对下列的句式进行句型改变,使其意义不变。 1. What he said at the meeting was of great value. ( ) 2. This medicine is of little use. ( ) 3. They are of great help to learners of English. ( ) 4. I don't want to hear what you are saying. It is of no interest to me. ( )