通井作业施工前应选择通井规,其最大外径要求比所通套管内径小()mm,长度为0.3~0.5m,并具有内通孔。
A.2-4
B.2-6
C.6-8
D.8-12
参考答案:C
Can you please tell me where ______ the post office? [ ]
A. to find
B. can I find
C. I can find out
D. find