下套管前的准备工作包括（）
A.检查套管和接头的丝扣
B.核实套管规格、数量
C.套管夹板和卡瓦
D.丝扣油、麻线
参考答案：A, B, C, D
— He's no use at all.
— _____, I have found him of a great deal of use. [ ]
A. First of all
B. Generally speaking
C. Believe or not
D. On the contrary
森林分类经营是以（）经营目标为依据的组织经营模式，便于目标管理。
