下列属于非可再生资源的是[ ]
A.石油
B.土地
C.水
D.森林
答案:A
David his friend’s invitation to the picnic in order to stay at home and study for the test.
A. expected B. refused C. received
无粘结预应力砼的优点是()
A.降低了楼层高度,提高了结构整体性能和刚度
B.不需要预留孔洞,穿筋和灌浆等工序
C.预应力筋强度能充分发挥
D.施工方便,工期短
E.锚具质量要求不高