单选题
桩身混凝土应在（）安装挡土板。
发布日期：2021-07-26
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试题解析
挡土板
挡土板是为了防止沟槽、基坑土方坍塌的一种临时性的挡土结构，一般由撑板和横撑组成，常用钢、木、竹制作。按横撑所使用的材质可分为木支撑和铁支撑，木支撑用圆木或方木制作横撑，铁支撑是专用的铁撑脚作横撑。钢制桩挡土板支撑是在沟槽、基坑开挖前用打桩机械打入槽型钢板桩，打好桩后，在开挖土方的同时，设置横撑对槽型钢板桩进行加固。
- 中文名
- 挡土板
- 材料
- 钢、木、竹
- 组成
- 撑板和横撑
应在
[元]字止善，句章（今浙江宁波南）人。工篆，尝作篆隶偏傍点画辨行於世。《书史会要》
- 本名
- 应在
- 所处时代
- 元代
- 字
- 止善
- 出生地
- 句章
安装
安装，汉语词汇，就是按照一定的程序、规格把机械或器材固定在一定的位置上，也指按照一定的方法、规格把机械或器材等固定在一定的地方。
- 中文名
- 安装
- 出处
- 《石油头》
- 拼音
- ān zhuāng
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Instructions:In this section, there is one passage followed by a summary. Read the passage carefully and complete the summary below by choosing no more than three words from the passage. Remember to write the answers on the Answer Sheet. Answers 1-5 are based on the following passage. Insects entombed in fossilised amber for tens of millions of years have provided the key to creating a new generation of antibiotic drugs that could wage war on modern diseases. Scientists have isolated the antibiotics from microbes preserved either inside the intestines of the amber-encased insects or in soil particles trapped with them when they were caught by sticky tree resin up to 130 million years ago. Spores of the microbes have survived an unprecedented period of suspended animation, enabling scientists to revive them in the laboratory. Research over the past two years has uncovered at least four antibiotics from the microbes and one has been able to kill modern drug-resistant bacteria that can cause potentially deadly diseases in humans. Present-day antibiotics have nearly all been isolated from micro-organisms that use them as a form of defence against their predators or competitors. But since the introduction of antibiotics into medicine 50 years ago, an alarming number have become ineffective because many bacteria have developed resistance to the drugs. The antibiotics that were in use millions of years ago may prove more deadly against drug-resistant modern strains of disease-causing bacteria. Raul Cano, who has pioneered the research at the California Polytechnic State University at San Luis Obispo, said the ancient antibiotic had been successful in fighting drug-resistant strains of staphylococcus bacteria, a “superbug” that has threatened the health of patients in hospitals throughout the world. He now intends to establish whether the antibiotic might have harmful side effects. “The problem is how toxic it is to other cells and how easy it is to purify.” said Cano. A biotechnology company, Ambergene, has been set up to develop the antibiotics into drugs. If any ancient microbes are revived that resemble present-day diseases, they will be destroyed in case they escape and cause new epidemics. Drug companies will be anxious to study the chemical structures of the prehistoric antibiotics to see how they differ from modern drugs. They hope that one ancient antibiotic molecule could be used as a basis to synthesise a range of drugs. There have been several attempts to extract material such as DNA from fossilized life-forms, ranging from Egyptian mummies to dinosaurs, but many were subsequently shown to be unsuccessful. Cano’s findings have been hailed as a significant breakthrough by scientists. Edward Golenberg, an expert on extracting DNA from fossilized life-forms at Wayne State University in Detroit, said: “They appear to be verifiable, ancient spores. They do seem to be real.” Richard Lenski, professor of microbial ecology at Michigan State University, said the fight against antibiotic-resistant strains of bacteria, such as tuberculosis and staphylococcus, could be helped by the discovery. However, even the discovery of ancient antibiotics may not halt the rise of drug- resistant bacteria. Stuart Levy, a micro-biologist at Tufts University in Boston, warned that the bacteria would eventually evolve to fight back against the new drugs. “There might also be an enzyme already out there that can degrade it. So the only way to keep the life of that antibiotic going is to use it sensibly and not excessively.” he said. Summary Microbes that may supply new antibiotic drugs have been 1 in the bodies of fossilised insects. The discovery may help destroy 2 bacteria. What needs to be done now is to find out how 2 hey are to humans. It is thought that a single antibiotic molecule could lead to a whole series of new drugs. Other scientists who have tried to produce antibiotics in a similar way have been 3 Scientists think Cano’s findings are a 5 breakthrough in the fight against diseases.
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