2FeCl₃ ; P₂O_{5 đọc là gì vậy giải thích rõ giúp mk}

BT1: Điền từ thích hợp vào ô trống

Forests are useful to man in several(1) ............. Woods is always neccessary for (2)............. and for making all kinds of things and we usually need firewood in our homes. Forest(3)............... timber - one of the most valuable(4)............. but they must be used wisely and managed carefully. Men should control the cutting of trees in such a way that the forest grows more trees than itwould be cut, leaving the young ones to grow(5)........... Trees and shu\rubs are also needed to preserve(6)............. beacause their roots bind the soil,(7)................ heavy rain from washing the soil(8)................