【单选题】
相对来讲，决定混凝土成本的材料是 ___
A. 水
B. 水泥
C. 砂子
D. 石子
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答案
B
解析
暂无解析
相关试题
【单选题】
当混凝土拌合物流动性偏大时，可以采取的调整措施是 ___
A. 保证水灰比不变的情况下，增加水泥浆数量
B. 保证砂率不变，增加砂石用量
C. 先增大水灰比的情况下，增加水泥浆数量
D. 直接加水
【单选题】
砂率的高低表示___。
A. 混凝土拌合物中细骨料所占比例的多少
B. 混凝土拌合物中水和骨料所占比例的多少
C. 混凝土拌合物中水泥所占比例的多少
D. 混凝土拌合物中外加剂所占比例的多少
【单选题】
混凝土的抗冻性用抗冻等级___来表示，抗冻等级为8 的混凝土表示其 ( C )。
A. 抗冻强度8MPa
B. 抗冻温度为一8°C
C. 抗冻融循环次数为8次
D. 抗冻时间为8小时
【单选题】
配置混凝土时，确定砂率主要应考虑的是 ___。
A. 混凝土的工作性和节约水泥两个方 面
B. 混凝土的强度和耐久性
C. 水泥的凝结时间和混凝土的抗冻性
D. 降低混凝土拌合物的保水性能
【单选题】
两种砂子，以下说法中正确的是___
A. 细度模数相同则级配相同
B. 细度模数相同但是级配不一定相同
C. 细度模数不同但是级配不一定相同
D. 级配相同则细度模数不一定相同
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【判断题】
（3） As the effects of drugs are often characterized by significant interspecies variation and may be further modified by disease, clinical pharmacology has never been efibrasized.
A. 对
B. 错
【判断题】
The physician is not interested in drugs that are useful in the prevention,diagnosis,and treatment of human disease, but in chemical agents that are commonly responsible for household and industrial poisoning as well as environmental pollution.
A. 对
B. 错
【判断题】
(5)A drug is said to be useful in therapy if it has the ability to produce its desired effects with only tolerable undesired effects.
A. 对
B. 错
【判断题】
(6)Toxicology deals not only with drugs used in therapy but also with many other chemicals that may be responsible for household, environmental, or industrial intoxication.
A. 对
B. 错
【判断题】
1)With the more efficient screening tests and burgeoning knowledge about how a molecules biological activities are likely to be changed, the traditional approach of discovering new drugs has been improved.
A. 对
B. 错
【判断题】
2)With the parallel synthesis used to identify which small segment of any given large protein would bind to an antibody, Mario Geysen generated a variety of short protein fragments by combining multiple amino acids in different permutations.
A. 对
B. 错
【判断题】
)A parallel synthesis and a split-and-mix synthesis are different in that in a split-and-mix synthesis, all the products are assembled separately n their respective reaction vessels.
A. 对
B. 错
【判断题】
4) In many laboratories, robots are used in the routine work of parallel synthesis to deliver small amounts of reactive molecules into appropriate wells, thus making the process more accurate and less tedious.
A. 对
B. 错
【判断题】
5) In a parallel synthesis, each compound remains in its own container; while in a split-and-min synthesis, the related ce mpounds are mixed up in the same reaction vessel.
A. 对
B. 错
【判断题】
6)In order to solve the difficulties of identifying the compounds made in a parallel synthesis scientists pull out from the mixture the beads that bear biologically active molecules and determine the molecular makeup o d attached.
A. 对
B. 错
【判断题】
1)The concentration of a drug in whole plasma is the most accurate index of the drug concentration at the site（s） of action.
A. 对
B. 错
【判断题】
(2)It is difficult to measure the total concentration of both unbound and bound drug in total plasma.
A. 对
B. 错
【判断题】
(3)The clinical effect of a drug is assumed to be directly related to the plasma drug concentration.
A. 对
B. 错
【判断题】
(4) Systemically acting drugs administered by all routes involve the absorption of drug from the place of administration into the blood.
A. 对
B. 错
【判断题】
5)Bioavailability of a drug indicates whether a therapeutically effective concentration is achieved at the site(s)of action of that drug.
A. 对
B. 错
【判断题】
(6)Prodrugs are not therapeutically effective unless they are changed into therapeutically active forms before or after reaching the systemic circulation
A. 对
B. 错
【单选题】
（3）生物圈的范围为___
A. 大气圈、水圈和岩石圈的全部
B. 大气圈和水圈的全部、岩石圈的上部
C. 大气圈的底部、水圈和岩石圈的全部
D. 大气圈的底部、水圈的全部和岩石圈的上部
【单选题】
（8）地球的表面积约为5.1亿平方千米，表面起伏不平，凸出来的地方成为陆地和山脉，而大片大片下凹的部分经过亿万年的积累，被液态海水所淹没而变成了海洋，海洋面积占地球表面积的近___。
A. 2％
B. 51%
C. 71%
D. 91%
【单选题】
（22）由于水的时空分布问题，经常造成我国不少地区的自然灾害。下列灾害的地区分布格局，属于符合我国一般规律的是 ___
A. 北涝南旱
B. 东涝西旱
C. 南涝北涝
D. 西旱东旱
【单选题】
（25）我国正在建设中的“三峡水利枢纽工程”主要是为了解决___
A. 水污染问题
B. 水资源时间分配不均的问题
C. 水资源空间分布不均的问题
D. 水资源总量不足的问题
