( Based on the growth rates of large modern reptiles such as ) the Galapagos tortoise and examination of fossils of juvenile dinosaurs, scientists estimate that the larger dinosaurs probably lived to be between 100 and 200 years old. A. Based on the growth rates of large modern reptiles such as B. On the basis of growth rates of large modern reptiles such as C. Based on the growth rates of large modern reptiles like D. On the basis of growth rates of large modern reptiles, like those of E. Based on the growth rates as those of large modern reptiles like 答案是B，错选了A。科学家基于爬行动物的生长率，估计了恐龙的存活时间。科学家做based on的逻辑主语有错吗？麻烦老师讲解。 (Based on account of various ancient writers) , scholars have painted a sketchy picture of the activities of an all-female cult that, perhaps as early as the sixth century B.C, worshipped a godness known in Latin as Bona Dea "the good goddess". A. Based on account of various ancient writers B. Basing it on various ancient writer's accounts C. With accounts of various ancient writers used for a basis D. By the accounts of various ancient writers they used E. Using accounts of various ancient writers 答案是E，还是错选了A。做题时在AE纠结了好久，因为不确定学者作为“基于不同作家的解释”的主语是不是错的，而且感觉基于要比使用的表达更好，尽管可以确定using的主语是学者，但还是把E排除了，麻烦老师讲解。 因为不知道这两道题是犯了什么错误，所以去有道查了based on 的例句，发现人是可以做主语的：Based on the finding, one might predict that the bank should increase its display and budget. 以及 Based on that representation, the district judge denied a motion to dismiss the new comlaint. 麻烦老师讲解这几个题的区别。

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