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【单选题】
日常教学中的 PPT采用下列哪种配色方案能得到最好的展示效果?A.
蓝色 +紫色
B.
红色 +绿色
C.
白色 +黑色
D.
白色 +灰色
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反馈参考答案：
举一反三
【多选题】What are the functions of reverse transcriptases?
A.
Reverse transcriptases catalyze three different reactions: (1) RNAdependent DNA synthesis, (2) RNA degradation, and (3) DNA-dependent DNA synthesis. Like many DNA and RNA polymerases, reverse transcriptases contain Zn 2+ .
B.
Each transcriptase is most active with the RNA of its own virus, but each can be used experimentally to make DNA complementary to a variety of RNAs. The DNA and RNA synthesis and RNA degradation activities use separate active sites on the protein. For DNA synthesis to begin, the reverse transcriptase requires a primer, a cellular tRNA obtained during an earlier infection and carried in the viral particle.
C.
This tRNA is base-paired at its 3′ end with a complementary sequence in the viral RN The new DNA strand is synthesized in the 5′ → 3′ direction, as in all RNA and DNA polymerase reactions. Reverse transcriptases, like RNA polymerases, do not have 3′ → 5′ proofreading exonucleases.
D.
They generally have error rates of about 1 per 20,000 nucleotides added. An error rate this high is extremely unusual in DNA replication and seems to be a characteristic of most enzymes that replicate the genomes of RNA viruses. A consequence is a higher mutation rate and faster rate of viral evolution, which is a factor in the frequent appearance of new strains of disease-causing retroviruses.
【单选题】根据《建设工程工程量清单计价规范》(GB 50500—2008)的规定，下列选项中，不属于按设计图示尺寸以面积计算墙面镶贴块料的是( )。
A.
石材墙面
B.
碎拼石材墙面
C.
装饰板墙面
D.
块料墙面
【多选题】下列选项中，属于塑料板面层一般项目的是（）
A.
塑料板面层所用的塑料板块卷材的品种、规格、颜色、等级应符合设计要求和现行国家标准的规定
B.
板块的焊接，焊缝应平整、光洁，无焦化变色、斑点、焊瘤和起鳞等缺陷，其凹凸允许偏差为±0.6mm。焊缝的抗拉强度不得小于塑料板强度的75%
C.
塑料板面层应表面洁净，图案清晰，色泽一致，接缝严密、美观。拼缝处的图案、花纹吻合，无胶痕；与墙边交接严密，阴阳角收边方正
D.
镶边用料应尺寸准确、边角整齐、拼缝严密、接缝顺直
E.
面层与下一层的粘接应牢固，不翘边、不脱胶、无溢胶
【单选题】关于太极二章第一步，下列叙述正确的是：
A.
向左侧转身成左前侧丁字步，左手下格挡。
B.
向右侧转身成右前侧丁字步，左手下格挡。
C.
向左侧转身成左前侧丁字步，右手下格挡。
D.
向左侧转身成左前侧弓步，左手下格挡。
【单选题】What is the difference between a reverse auction and mass customization?
A.
Reverse auction is most often found in B2B whereas mass customization is often found in B2C.
B.
Reverse auction requires a bid from consumers whereas mass customization requires a bid from suppliers.
C.
Mass customization require a click-and-mortar environment; reverse auctions do not.
D.
Mass customization can sell digital products; reverse auctions sell commoditylike products.
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