抽油杆脱扣原因有几种？_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题问答题简答题

抽油杆脱扣原因有几种？

答案

参考答案：

抽油杆的离心力、井下异常工况、抽油杆反转、螺杆泵的排出口与吸入口压差大、预紧力不足、螺纹失效。

单项选择题

甲、乙、丙三堆棋子共98粒。小文先从甲堆里分棋子给乙、丙两堆，使乙、丙两堆棋子数各增加一倍；再把乙堆的棋子照上面那样分配给甲、丙两堆；最后又把丙堆的棋子仍照上面那样分配给甲、乙两堆。结果甲堆的棋子是丙堆棋子的，乙堆棋子是丙堆棋子的。原来丙堆有多少粒棋子（）

A．6

B．16

C．30

D．32

完形填空

Long ago there was a poor farmer in Russia. He had been very__1__with everything he had. However，when he found his elder brother was_2__than him，he felt disappointed. So he__3_hard about how he could also be richer. Finally he got an idea. He started to spend less money on food and clothes to__4__some money to buy more land. Once he had enough money，he started__5_for land.
He__6__that on the neighboring land，there were some nomads (游牧民) living there. He bought some gifts and went to__7__their head. He presented the gifts to the head and told him the__8__of his visit. The head welcomed him，accepted the gifts and agreed to his_9__to get the land. The head told him that he could have the land__10__giving him anything. He can take as much land as he could__11__by walking through the land before sunset (日落)．He should start in the morning and whatever distance he could travel during the__12_，he could have it.
The farmer became very__13__when he heard this offer. Now he could have lots of__14__without paying anything. He came_15_the next morning and started running，not walking，__16__he could cover the largest area. To reach his goal，he neither ate food，nor drank water，nor had any rest. He just continued__17__.Without eating，or drinking，or resting he just got very__18__.When he came back to the head in the evening，he__19__right on the spot. Sadly his son buried him in a piece of land about 6 x 4 feet.
Don’t be greedy (贪婪的) or you will__20__everything finally.

A．careful　　　

C．bored　　　