She has the ability to keep___in an emergency.

A.ambition

B.appetite

C.aptitude

D.ability

A.comes

B.came

C.will come

D.has come

A.lives

B.lived

C.has lived

she _____________ too long.

A) has been reading B) had read

C) is reading D) read

A.has

B.is

C.can

D.must

She ought to stop work；she has a headache because she ______ too long.

A) has been readingB) had readC) is readingD) read

y keep on asking her until she ________.

A) does B) has done C) will do D) would do

she has to take on such heavy _____ housework as carrying water and firewood.

A) timeconsumed B) timelyconsumed C) timeconsuming D) timely

thinks that if she __________ a job she probably wouldn’t be able to see her friends very often.

A) has to get B) were to get

C) had got D) could have got

【题目描述】

44. Helen loves to talk about travel. She _____ many places. A. has gone to B. has been to C. has gone for D. has been from

【我的疑问】（如下，请求专家帮助解答）

has gone to 与has been to的区别

截取一段明文如下:

The Mutual Information Analysis (MIA) is a generic side channel distingui she that has been introduced at CHES 2008. This paper brings three contributions with respect to its applicability to practice. First, we emphasize that the MIA principle can be seen as a toolbox in which different (more or less effective) statistical methods can be plugged in. Doing this, we introduce interesting altematives to the original proposal. Second, we discuss the contexts in which the MIA can lead to successful key recoveries with lower data complexity than classical attacks such as, eg. using Pearson's correlation coefficient. We show that such contexts exist in practically meaningful situations and analyze them statistically. Finally, we study the connections and differences between the MIA and a framework for the analysis of side- channel key recovery published at Eurocrypt 2009. We show that the MIA can be used to compare two leaking devices only if the discrete models used by an adversary to mount an attack perfectly correspond to the physical leakages.

忽略文中的数字和符号，试用(1.9)仿射密码加密。然后对密文进行破密。