adj.不能穿過的；不可理喻的
Armor plate is impenetrable by ordinary bullets. 裝甲板普通子彈打不穿。
Some wild pheasants love impenetrable jungles. 有些野雉喜歡生活在密密的叢林里。
This history book is completely impenetrable to me. 這本歷史書我完全看不懂.
