井控设计时,在选择井控设备前,需要对()和井眼尺寸、套管尺寸、套管钢级、井身结构等做详尽的了解。
A、地层破裂压力
B、地层压力
C、井底压力
D、地层坍塌压力
参考答案:B
The town _______ we visited last month is the one _______ the famous painter was born.
A.where; which
B.which; where
C.which; that
D.where; where
设有不同的直线a,b和不同的平面α,β.给出下列命题:
①若a∥α,b∥β,且a∥β,则a∥b ②若a⊥α,b⊥β,且α⊥β,则a⊥b
③若a∥α,b∥β,且a∥b,则a∥β ④若a⊥α,b⊥β,且a⊥b,则α⊥β其中正确的题号是______.