The practical value of knowledge resources possesses popularity , duality of exhaustiveness and non exhaustiveness, and expansivity.知识资源的使用价值具有广普性、非耗竭与耗竭二重性及扩张性....
托马斯在一小块围起来的满是沙子的地上玩耍。Thomas was playing in a little fenced area full of sand.这个水池很危险,应该用栅栏围起来.The pool is dangerous and should be fenced off.崖边危险,应该用栏杆围起来.The cliff edge is dangerous and should be railed....