Archaeology as a profession faces two major problems. First, it is the poorest of the poor. Only paltry sums are available for excavating and even less is available for publishing the results (5) and preserving the sites once excavated. Yet archaeologists deal with priceless objects every day. Second, there is the problem of illegal excavation, resulting in museum-quality pieces being sold to the highest bidder. (10) Iwould like to make an outrageous suggestion that would at one stroke provide funds for archaeology and reduce the amount of illegal digging. Iwould propose that scientific archaeological expeditions and governmental (15) authorities sell excavated artifacts on the open market. Such sales would provide substantial funds for the excavation and preservation of archaeological sites and the publication of results. At the same time, they would break the illegal (20) excavator's grip on the market, thereby decreasing the inducement to engage in illegal activities. You might object that professionals excavate to acquire knowledge, not money. Moreover, ancient artifacts are part of our global cultural heritage, (25) which should be available for all to appreciate, not sold to the highest bidder. Iagree. Sell nothing that has unique artistic merit or scientific value. But, you might reply, everything that comes out of the ground has scientific value. Here we part company. (30) Theoretically, you may be correct in claiming that every artifact has potential scientific value. Practically, you are wrong. I refer to the thousands of pottery vessels and ancient lamps that are essentially duplicates of (35) one another. In one small excavation in Cyprus, archaeologists recently uncovered 2,000 virtually indistinguishable small jugs in a single courtyard. Even precious royal seal impressions known as I'melekh handles have been found in abundance (40) —more than 4,000 examples so far. The basements of museums are simply not large enough to store the artifacts that are likely to be discovered in the future. There is not enough money even to catalog the finds; as a result, they 368 (45) cannot be found again and become as inaccessible as if they had never been discovered. Indeed, with the help of a computer, sold artifacts could be more accessible than are the pieces stored in bulging museum basements. Prior to sale, each could be (50) photographed and the list of the purchasers could be maintained on the computer. A purchaser could even be required to agree to return the piece if it should become needed for scientific purposes. It would be unrealistic to suggest that illegal (55) digging would stop if artifacts were sold on the open market. But the demand for the clandestine product would be substantially reduced. Who would want an unmarked pot when another was available whose provenance was known, and that was dated (60) stratigraphically by the professional archaeologist who excavated it? The primary purpose of the passage is to propose (A) an alternative to museum display of artifacts (B) a way to curb illegal digging while benefiting the archaeological profession (C) a wayto distinguish artifacts with scientific value from those that have no such value (D) the governmental regulation of archaeological sites (E) a new system for cataloging duplicate artifacts

GMAT数学（博智教材）第62页：If X is equal to the sum of the even integers from 40 to 60, inclusive, and y is the number of even integers from 40 to 60, inclusive, what is the value of x+y? X=40+42+44......60=550 Y=(60-40)/2+1=11, 答案应该是561，为什么书后面的答案显示是560？

数学书61页36题，一个男的卖每条7块的领带和每件14元的衬衫。如果他总共卖了10件，110元，求卖了几条领带？ 我得小数，选项里没有。

DS：5个数中 median 小于 average ；另外7个数也median 小于 average，然后这12个数没有重复的，12个数放在一个数集里面，问是不是median 小于average？ 条件1：7个的average 小于 5个的average 条件2：7个的median 小于 5个的 median

DS：一个三位数xyz是9的倍数，问x+y+z=9？ 条件1：x+y+z<15 条件2：x+y+z>8

question

这种ds题目里面有比例关系的我特别弱，老师能帮我梳理一下这种题拿到药怎么入手吗

老师这个题目帮我讲解一下，机经答案我看了还是不明白。

这个题目机经写的特别复杂，老师能帮我讲一下吗

老师，能帮我梳理一下这个题目吗

题目：of the 200 students at college T majoring in one or more of the sciences, 130 are majoring in chemistry and 150 majoring in biology. If at least 30 of the students are not majoring in either chemistry or biology, then the number students majoring in both biology and chemistry could be any number from a) 20 to 50 b) 40 to 70 c) 50 to 130 d) 110 to 130 e) 110 to 150 问题：这道题能理解到是用集合的知识点，但是无论怎么做都无法突破，得到最后结果。还请老师讲解。谢谢