急问,由大全secB-21想到的yet用法~~

21. A peculiar feature of the embryonic mammalian circulatory system is that in the area of the heart the cells adhere to one another, beating in unison and adopting specialized orientations exclusive of one another.
(A) beating in unison and adopting
(B) they beat in unison while adopting
(C) beat in unison, and adopt
(D) beating in unison yet adopting
(E) even though they beat in unison and adopt
答案D

讨论帖解释是因为有转折关系所以用yet 而不是and. 可是我想起来OG上一到题如下:

OG184.As measured by the Commerce Department, corporate profits peaked in the fourth quarter of 1988 and have slipped since then, as many companies have been unable to pass on higher costs.
(A) and have slipped since then, as many companies have been unable to pass on higher costs
(B) and have slipped since then, the reason being because many companies have been unable to pass on higher costs
(C) and slipped since then, many companies being unable to pass on higher costs
(D) but, many companies unable to pass on higher costs, they have slipped since then
(E) yet are slipping since then, because many companies were unable to pass on higher costs

答案为A. 排除E的时态不说，其中OG对E的解释为: In E, yet also requires a comma before it..

可是为什么大全21 yet前没有逗号呢??

再者, 我觉得OG184这题也有转折的意思,但却用的是and 而非yet, 不知道为什么..

麻烦大家解释一下!!~~~

有没有知道的呀?? 帮忙看看哦..顶

I want to know it, too.

问得好，再加一例：

OG114: could carry 4 persons or eight hundred lbs of baggage yet was so light...

没有逗号。

请NN看看。

21.题的yet转折挺难的哦

因为在前面的意思是adhere to one another（依附于one another） 而后面是exclude to one another

有相反的意思，可能这里才能看出转折，不知道小弟的见解对吗〉？？？

大家评论吧！！！

AND 表示动作时间的一种顺序，YET表示的是一种同时性，这样可能清楚些！

我也是模糊记忆我再查查！我现在看语法也看得晕乎乎的！