重点讲解：
1. be known as 称为；叫做；认为；
例句：The violin is known as the queen of instruments.
小提琴有乐器皇后之称)|_k+#Q8DQ2。
2. cut down 砍倒（树木）；
例句：A vandal with a chainsaw cut down a tree.
一个故意破坏公物的人用链锯伐倒了一棵树C.9F6KxE_Hwrel6;。
3. pass down 使流传；
例句：Folk music has been passed down from one generation to another.
民间音乐是一代一代流传下来的(9M^1&Y#D&n0*)L*;。
4. for sure 无疑;肯定；
例句：Nobody knows the cause of the fire for sure.
没有人确切地知道大火的原因+IEyA2%!g6。
5. at the most 至多；最多；
例句：It will take two hours at the most to get there.
最多两小时便可到达那里d#WlwHljm6W9t^|ix%g。