BD：the river is xxx 是主系表结构，变成了focal point是river 的固有属性。但E里as a focal point是宾补结构，是have这个动作给与的。显然，focal point只能是被给与的，而不是本来有这个属性

choice d, this sentence has completely gotten rid of any reference to the concept of 'no longer'. while all the other sentences say that things have changed, this sentence presents the situation as if it's always been that way. While choice e, 'No Longer ' indicates a status change

look at the main structure of choice D:
"[modifier] + a river is the focal point of urban life, BUT the river in San Antonio winds through the middle of the business district and xxxx."
there's no contrast here at all! we have [modifier] + "things are built around rivers" + BUT + "even more things are built around rivers".
you can see that this is nonsense even if you have no idea what the sentence SHOULD say.

the correct answer here is still pretty ugly, so let's criticize the four incorrect choices.

choice a:
faulty comparison:
'unlike many u.s. cities, ... the river in san antonio...' --> can't compare cities to a river

choice b:
comparison isn't so good:
the second part should start directly with 'the river' (instead of 'in san antonio the river...'), so that the comparison is more clear.
much more importantly, poor use of the relative pronoun 'which':
'...cities in the united states, which is no longer the focal point...'
relative pronouns like which, by default, refer to the noun that's closest to the left, which in this case is the united states. therefore, this relative pronoun is used in a way that's either ambiguous (if you allow it to potentially refer to other nouns) or just plain wrong (if you follow the rule strictly).

choice c:
faulty comparison again
'the river...' is being compared to san antonio.

choice d:
drastic change in meaning
this sentence has completely gotten rid of any reference to the concept of 'no longer'. while all the other sentences say that things have changed, this sentence presents the situation as if it's always been that way.

1.比较对象
2.语义推理。No longer的句意在D中没有了。
E选项是否定句倒装表示强调。

No longer do many cities in United States have a river as the focal point of urban life
... is grammatically equivalent to ...
Many cities in United States no longer have a river as the focal point of urban life

also
Only yesterday were we told about the layoffs
... is equivalent to ...
We were told about the layoffs only yesterday

the primary difference between the examples in each pair is rhetorical. in particular, the first one in each pair -- the one that places the adverb (only yesterday, no longer) in front -- would be written that way in order to emphasize the meaning of that adverb. from the standpoint of grammar, there is essentially no difference.

the correct answer here is still pretty ugly, so let's criticize the four incorrect choices.

choice a:
faulty comparison:
'unlike many u.s. cities, ... the river in san antonio...' --> can't compare cities to a river

choice b:
comparison isn't so good:
the second part should start directly with 'the river' (instead of 'in san antonio the river...'), so that the comparison is more clear.
much more importantly, poor use of the relative pronoun 'which':
'...cities in the united states, which is no longer the focal point...'
relative pronouns like which, by default, refer to the noun that's closest to the left, which in this case is the united states. therefore, this relative pronoun is used in a way that's either ambiguous (if you allow it to potentially refer to other nouns) or just plain wrong (if you follow the rule strictly).

choice c:
faulty comparison again
'the river...' is being compared to san antonio.

choice d:
drastic change in meaning
this sentence has completely gotten rid of any reference to the concept of 'no longer'. while all the other sentences say that things have changed, this sentence presents the situation as if it's always been that way.

E的no longer有转变的意思，从前是现在不是了，D改变了意思，单纯比较一些城市没有而SA有，少了意思

'RON： few' is a negative construction. in this sense it works exactly like 'no'.
No animal has a green tongue. this is a negative statement. because it is fundamentally a statement about something that DOES NOT exist, the MAIN SENTENCE must contain a negative construction.

D选项，But前后的句子意思已经不再是转折，错误

no longer the focal point of urban life， 不再是城市生活的焦点，这里指河流
A: 前后对比不是城市和河流；
B: which就近修饰了城市，这里应该修饰river
C：与A错误一样
D: 用but 替代no longer, but感觉一直都是如此，但是no longer可以提现一个转变，句意已经变了
E: 倒装还原 Many cities in the United States no longer have a river as the focal point of urban life， But的对比不要求像unlike那么对称？

B：unlike对比有问题（A也是），与 the river in many cities in the United States相对应，the river in San Antonio 更好。which错误修饰the United States。
D：几乎没有美国城市把河流作为生活重点，但是SA的河流是生活重点。
E：很多城市不再把河流当做重点，但是SA的河流仍然是生活重点。
比较的点应该是这个 “no longer”，大多城市不再是……而SA仍然是……

DE的区别很明显，一个是做状语一个是做句子的主语，显然应该是城市是来作主语的，而不是去强调修饰”河流是中心“的是中心

B，前面有unlike the river，后面比较的对象river应该紧跟着出现，最好不要在中间插入in San Antonio
D，抛弃了no longer这个词，转用but来表示一个如何，另一个非如何。这种改变导致原句一个如何，另一个不再如何里的不再所包含的之前如此，后来不是的意思没有了，表意效果不好。
E，放弃了unlike，转用but来表示两件不同的事，并保留了no longer，无论语法还是语意逻辑都是ok的。

d选项表达的意思是在美国几乎没有城市里河流时城市生活的关注点。而其他的选项里表达的意思是在美国绝大多数的城市里，河流不再！！！是生活的关注点。前者的表达了一种不变的状态，而后者表达了一种变化。
D没有语法错误，而是句意错误
E还原倒装后的真实句子：in the United States many cities no longer have a river as... but in San Antonio

D/E的差异：
1、the river in San Antonio VS in San Antonio the river winds
2、in few cities，river……，but river in another city…… VS Many cities no longer have rivers ……，but in another city the river……
因为是转折逻辑，不要求两个句子的结构严格平行；
no longer把“很多城市之前也有河……，现在没了”表达出来了，语意更清晰。

D选项：原句中有no longer体现前后的一种变化，但是d少了这次意思［语意啊语意！！！］

E还原倒装后的真实句子：in the United States many cities no longer have a river as... but in San Antonio

许多城市的河流不再是城市生活的一个核心标志，但是SA的河流经过核心商业区，RW是这个城市最著名的景点。句子想要表达的是河流和河流作比较
unlike的介词宾语需要和主句的主语做对比，排除choice a,b
choice c, it指代river in many cities
choice D: in few cities作状语修饰的是主句的系动词is; 而根据身后未划线的river in SA可知，城市是作为定语修饰river的。
去掉修饰看核心成分：a river is the focal point of urban life, but the river in San Antonio winds through the middle of the business district. 简化以后发现but前后是没法形成转折关系的

d缺少no longer，语意发生变化，no longer说明以前是，d缺少了这层意思