For some birds the sense of smell appears to paly a role in navigation, since pigeons with surgically removed olfactory nerves ( were found to have increased difficulties ) in homing.
A. were found to have increased difficulties
B. have been found to have increased difficulty
C. were found to have increasing difficulty
D. had been found to have increased difficulties
E. have been found to have increasing difficulties
答案是B,我选的A。不明白为什么要用现在完成时,而且感觉困难应该是复数。麻烦老师讲解。
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调查1200人对A B C 的喜好,喜欢A的40%,喜欢B的58%,喜欢C的40%,同时喜欢AB的30%,求喜欢C但不喜欢A B的人
题目:A Printer numbered consecutively the pages of a book, beginning with 1 on the first page. In numbering the pages, he printed a total of 189 digits. How many pages are there in the book?
问题:看了中文翻译并听了管老师的讲解,我都没弄明白这个题目的解题思路。的别是对“a total of 189 digits”的处理。
题目:If n is a prime number greater than 3, what is the remainder when n的平方is divided by 12?
问题:当管老师解题时,他出了3个方程式,分别是:
1) n=3A+1, n的平方=9A(square)+6A+1
2) n=3A+2, n的平方=9A(square)+12A+4
3) n=2A+1, n的平方=4A(square)+4A+1
我不明白的点是:这3个方程式是怎么推到或者是一看到题目就这么设出来的?