问题 问答题 简答题

在人工顶板网下作业应注意什么事项?

答案

参考答案:在人工顶板网下作业时虽然顶压不大,但最大的危害是顶网破损,造成网上碎石大量涌出,严重量无法进行采煤作业,所以在开采网下工作面应注意:

(1)工作面初采时,要先从开切眼向后开采到顶网边缘,支柱与网边留一定距离,使上分层预留的网卷能从支柱后边漏下来,然后再向前回采。回柱时一定要注意保证落网质量,并及时处理顶网出现的问题。

(2)正常回采时,最大和最小控顶距都不宜过大,使用悬臂梁支架宜用三、四排或三、五排支护方式,并要让网片搭接部位在顶梁中部,顶网下沉量应控制在0.4m以内。为了防止放顶后网后采空区石块推网,可用戗柱将末排支柱或悬网戗住。

(3)工作面回风巷的上帮和运输巷的下帮网片应联结到底板,使它随两巷支架不断向前回收,能顺利地随工作面顶网一并落到底板,有效的维护着上下安全出口。

阅读理解

阅读理解。

     Barefoot Traveler is a tour agent that specializes in diving holidays, tailor-made to your own needs. The

most popular destinations include Bonaire, Tobago, the Bahamas, Maldives,Oman, Seychelles and Thailand.

     Our friendly and knowledgeable staff, who are qualified divers (潜水员) themselves, will be able to advise

you on the best destinations for your requirements.

     Whether you want to learn to dive, further your diving qualifications, continue to discover the underwater

world, or simply relax on the beach, we are here' to help organize your holiday.

     We are happy to satisfy single travelers and offer special discounts (折扣).

     Group discounts are offered to groups of eight or more travelers and tailor-made packages are available for

Dive Clubs.

     We also offer a series of diving live aboard choices throughout the Caribbean. Indian Ocean and South East

Asia. Live aboards are very popular scuba (呼吸器) diving holidays for those who want to access the best

diving sites.

     Our barefoot luxury holiday brand is for those trying something a little more special, whether it's your

honeymoon, anniversary or simply for more discerning (有品位的) travelers. We have a selection of 4 and 5

star levels which are the best in luxury holidays.

1. What's the author's purpose in writing this passage?

A. To give some advice on diving.

B. To introduce the popular destinations.

C. To teach diving skills.

D. To attract tourists.

2. Which of the following is TRUE according to the passage?

A. It's impossible to be offered tailor-made packages when you join Dive Clubs.

B. Au staff are qualified divers with wide knowledge on the best diving.

C. Barefoot Traveler specializes in simple holidays.

D. Travelers can enjoy Winter Sun.

3. According to the passage, Barefoot Traveler _____.

A.is not a tour agent

B. has over 25 scuba diving liveaboard beats

C. makes the luxury holiday based on consumers' needs and desires

D. makes the luxury holiday you don't have in mind

4. The best title for this passage would be _____.

A. Welcome to Barefoot Traveler

B. A Wonderful Experience

C. Scuba Diving

D. How to Choose Destinations

单项选择题