Let z=3, x=0, y=2t, ∴ n 1 = (0, 2t, 3)...( 12) ... From (i), it is known that AF⊥ plane CFB, and a normal vector of plane CBF is N2 = AF. n2|n 1|？ |n2|, which means 12=.
(20 14? In the picture on the right, X is the power supply, and Y is the saturated salt solution and phenolphthalein test. Love A, when electrified, the electrons of hydrogen ions in saturated brine precipitate on the C electrode, which leads to the increase of the concentration of hydroxyl ions near the C electrode and the enhancement of the alkalinity of the solution, so the test solution dripping with phenolphthalein will turn red, so A is correct. B, when electrified, copper is used as the cathode and platinum is used as the anode, and the quality of the copper electrode is increased due to the electrons of copper ions on the copper electrode. The quality of the platinum electrode remains unchanged because the hydroxyl ion on the platinum electrode loses electrons, so B is wrong. C. When electrifying, copper is used as cathode, platinum is used as anode, copper ions on copper electrode get electrons to precipitate copper, and hydroxyl ions on platinum electrode lose electrons to generate oxygen, which leads to the increase of hydrogen ion concentration in solution and the decrease of PH value of solution, so C. Wrong. D. When electrifying, the anions in the electrolytic cell move to the anode and the cations move to the cathode.
(20 14? Yimo, Zhengzhou) In order to welcome the arrival of 20 14 Year of the Horse, a school held a prize-guessing activity, in which the probability of randomly guessing A is P 1= 13, and the probability of randomly guessing B is P2 = 14...(2 points) (/kloc-0. P2)= 13*34= 14, that is, the probability of participants answering question a first is 14...(4 points) (2) There are two orders for participants to answer questions, which are discussed as follows: ① Answer question A first, then answer question B, and the prize amount of participants can be 0. P2) = 13 * 34 = 14，p(ξ= a+b)= p 1p 2 = 1 12，∴ E ξ = 0 * 23+A * 65448。 Then p (η = 0) = 1-P2 = 34, p (η = b) = (1-p1) p2 =16, and p (η = a+b) = P2P/kloc-. 2b 12 Therefore, when ab & gt23, E ξ > Eη, that is, answer question A first, then answer question B, and the expectation of winning the prize is greater; When ab=23, user 20 1 7-120 gives an error (1), and the probability of randomly guessing question A is P 1= 13, and the probability of randomly guessing question B is p2 =/kloc-0. Using the multiplication formula of probability, participants can be asked to answer question A first. (2) There are two orders for participants to answer questions: first answer question A, then answer question B, then answer question B and then answer question A, and compare the winning expectations of the two situations and discuss them in different categories. Probability of equally probable events. Test center comments: This question examines the calculation of probability and expectation. Expectation is one of the important concepts in probability theory and mathematical statistics, and it is a characteristic number reflecting the distribution of random variables. Scan and download QR code? 2020 ? Contact information: service @ Zuo Yebang? The agreement Var user city = "\ u53 17 \ u4EAC ",user province = "\ u53 17 \ u4EAC", and Wen Zuo Small = "2.
(20 14? There are different records about Grandpa Cao's life experience in Jing 'an District: First, (1) Cao Ding and Cao Teng are blood brothers, and their Y chromosomes are all from their fathers, which are exactly the same. Cao Teng inherited the Y chromosome from Cao Cao, so it can be inferred that the Y chromosome is consistent. Therefore, the relationship between Cao Teng and Cao can be inferred from the gene of Y chromosome. (2) Because somatic cells are produced by the mitosis of fertilized eggs, all somatic genetic materials are the same, but in the process of cell differentiation, due to the selective expression of genes, the morphology, structure and function of different tissues and cells are very different. (3) PCR can be used to amplify DNA molecules known in bioengineering technology. (4) The frequency of gene mutation is very low, and the probability of the same gene mutation at the same gene locus is even lower among ethnic minorities. (5) As can be seen from Figures 2 and 3, the restriction endonuclease EcoRI has two restriction endonuclease cleavage sites on the DNA molecule. However, when EcoRI and Hind Ⅲ cut at the same time, it was found that 200p.p disappeared and 100p.p appeared, which indicated that Hind Ⅲ had a cutting site in the middle of 200 p.p: 700p.p became two kinds of fragments, 420p.p and 280p.p, which indicated that Hind Ⅲ enzyme had one in the fragment of 700 p.p. Accumulation in blood vessels can lead to hypercholesterolemia. (8) Because No.5 is normal and the genotype is rr, the genotype of 1 with mild receptor deficiency is RIr, while No.3 has two diseases at the same time, so its genotype is RIR II. (9) 10 and its ex-wife have no difficulty in transporting LDL into cells, but their children have difficulty in transporting LDL into cells. On the other hand, because the probability of FH patients with difficulty in transporting low-density lipoprotein into cells is 12500, that is, aa is 12500, A's gene frequency is 150, and A's gene frequency is 495 1AA, so the gene of a wife with normal phenotype is 495/kloc. There are six genotypes related to cholesterolemia on chromosome 19: RIrI, R2R2, RIR2, RIR, R2R and rr, so there may be 3*6= 18 genotypes in humans. So the answer is: (1)Y Cao Ding and Cao Teng are brothers, and their Y chromosomes both come from their fathers. Therefore, it can be inferred that the Y chromosome is consistent. (2) Genes are selectively expressed in different tissues and cells. (3)PCR technology. (4) The frequency of gene mutation is very low, and the probability of the same gene mutation at the same gene locus is even lower in small populations. (5)(6) recessive traits. (7) Low density lipoprotein is transported from hepatocytes to the periphery with a large amount of cholesterol, which affects the decomposition of cholesterol by the liver and accumulates in blood vessels. (8)