肾内的"蛋壳样钙化"，常见于下列哪种疾病（） A.甲状旁腺功能亢进 B.肾囊肿 C.

在SWOT模型矩阵中，第一象限是指（）并存。

A.威胁与劣势

B.机会与劣势

C.机会与优势

D.机会与威胁

用所给动词的适当形式填空。

     The village of Monsata was not a beautiful place.Most people    1    (not have)good houses. Many of them   2   (make) their houses out of old boxes and paper. And there   3   (be) no water. Women and children    4   (have) t   5   (walk) about two kilometers down the hill and   6   (carry)  water on their heads. Life became very hard there. But the village people still enjoyed   7   (live) there. They worked on their own land and on the weekend the whole village always   8   (dance) with music.

1.______2.______3.______4．______5.______6．______7.______8.______

抽油机曲柄销在曲柄圆锥孔内松动或轴向位移是什么原因？

试述苏联解体的影响

试根据GB5293—85，说明焊剂型号表示方法中各符号的含义。