语法笔记 139 these 单独做主语?

139. Besides adding complementary flavors to many foods, hot sauces stimulate the release of endorphins in the brain, just as exercise does, and these have a pain-relieving effect like morphine's.

A. hot sauces stimulate the release of endorphins in the brain, just as exercise does, and these have a pain-relieving effect like morphine's

B. hot sauces stimulate the release of endorphins in the brain, like exercise, and they have a pain-relieving effect that is like morphine

C. hot sauces and exercise both stimulate the release of endorphins in the brain, and they have a pain-relieving effect like morphine

D. the release of endorphins in the brain is stimulated both by hot sauces and exercise, and they have a pain-relieving effect like morphine's

E. the release of endorphins in the brain is stimulated by hot sauces, just as with exercise, and these have a pain-relieving effect like that of morphine

OA: A

不是有说法说these /those/that之类的词不能单独作为主语出现么?

各位高手帮帮忙吧

我只是个低手，不过想谈谈自己的体会：包括PREP在内的很多语法资料都强调过，语法题（或称改错题）是在选择“最佳”答案，而非“正确”答案。根据我做题的经验，有些题目会有一个以上的所谓从语法角度来说正确的答案，而有些题目的答案可能都有瑕疵，关键是要经过比较，得出一个最佳答案。就拿楼主所说的题目来讲，一上来就可以根据逻辑主语这一项而排除C,D,E。而B的最后一句话里的they根据并列原则应该指代hot sauces，可是这样的话逻辑不通，而即使逻辑意思通顺，and后面的句子和前面的句子主语一致，则they也应该省略。所以此题也只能选择A。

我觉得有些原则并非绝对，还是要看比较。

LiuxyMM,谢谢你的回复.

不过我还是有点迷茫的,B中they指代hot sauces 我觉得是没问题的,主句话的意思原本就是hot sauces能刺激大脑中E物质的发生,它的作用和吗啡是一样的.如果说they 只是指代重复的话,那就是个effective的毛病,但是代词的指代错误就是个corrective的毛病呀.

请指教,谢谢

B 中有两个不对的，1. 是like exercise。与前面的不平行，应该是 XXX do sth， just as XXX do

                   2.是that is like morphine.(不简洁），尽量不要使句子过于复杂，减少定语从句的修饰。