什么叫井壁压力梯度?
参考答案:
井壁压力梯度是指天然气从地层内流到井底时,在紧靠井壁附近岩石单位长度上的压力降。
蚂蚁等昆虫的足是______的,依靠足部______的收缩和舒张,使分节的足产生运动.运动时,一般以一侧的______和另一侧的______为一组,进行交替运动.
Jenny ________ a rich man. She has ________ him for 5 years.
A.married with; married with
B.married, been married to
C.married to; been married
D.married; married