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【单选题】
Careers Officers ______ contact with young people after they le ave school. A. B. C. D.A.
maintain
B.
contain
C.
obtain
D.
detain
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【简答题】父本基因型为AABb，母本基因型为AaBb，其F 1 不可能出现的基因型是（ ） A ．AABb B．Aabb C．AaBb D．aabb
【单选题】下列有关沉淀溶解平衡的说法正确的是（ ）
A.
K SP （AB 2 ）小于K SP （CD），则物质AB 2 的溶解度一定小于物质CD的溶解度
B.
在氯化银的沉淀溶解平衡体系中，加入蒸馏水，氯化银的K SP 增大
C.
在氯化银的沉淀溶解平衡体系中，加入碘化钾固体，氯化银沉淀可转化为碘化银沉淀
D.
在碳酸钙的沉淀溶解平衡体系中，加入稀盐酸，溶解平衡不移动
【多选题】Noncoding RNAs (ncRNAs) with different lengths have various roles, serving as regulatory, structural, and catalytic components of cells. Abundant and functionally important types of ncRNAs include tra...
A.
rRNAs form the structural and catalytic core of the ribosomes, which translate mRNAs into protein. tRNAs act as adaptors that select specific amino acids and hold them in place on a ribosome for their incorporation into protein.
B.
In higher eukaryotes, miRNAs regulate gene expression. A single miRNA can reduce the expression levels of hundreds of genes. The mechanism by which mature miRNA molecules act is through partial complementary to one or more mRNA molecules, generally in 3'-UTR. The main function of miRNAs is to down-regulate gene expression. Many other ncRNAs are involved in RNA splicing, gene regulation, telomere maintenance, and many other cellular processes.
C.
Piwi-interacting RNAs (piRNAs) expressed in mammalian testes and somatic cells form RNA-protein complexes with Piwi proteins. These piRNA complexes (piRCs) have been linked to transcriptional gene silencing of retrotransposons and other genetic elements in germ line cells, particularly those in spermatogenesis.
D.
The more conserved ncRNAs are thought to be molecular fossils or relics from the last universal common ancestor and the RNA world, and their current roles remain mostly in regulation of information flow from DNA to protein .
【单选题】关于金属零部件全寿命流程图，以下说法正确的是（）
A.
金属零部件的失效分析无关紧要；
B.
金属零部件的失效分析仅针对某一两个流程环节；
C.
金属零部件的失效分析涉及到其失效前的所有流程环节；
D.
金属材料和金属零部件的分析方法是一样的。
【单选题】黄慧敏 第二节 60.某旅行团按计划将于次日乘早班飞机离开某市,而餐厅无法提供 正常 早餐。在这种情况下,低配的正确做法是()。
A.
与餐厅经理交涉，要求餐厅提供早餐
B.
帮助旅游者提前在外卖店代购
C.
请旅游者自行解决次日的早餐
D.
请餐厅提前准备简便的餐食
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