According to the statistics, listening to loud music at rock concerts ______ hearing loss in some teenagers in the past 2 decades.

Mom,         my friends, Dave and Jack.

---How did your students express their thanks to you on Teachers’ Day?---A gift together with many flowers ______ sent to me. 

Since the forest has been destroyed by a big fire, a large ______ of trees ______ to be planted on the mountain．

 The poor ________ living in the mountain ________ top is covered with green trees.