[求助]救命！刘振民的《语法改错精解》

这本书狂打击我，每次练习都要错1/3至1/2，自信心狂受打击，有些地方研究半天也研究不出个什么来，请各位大侠赐教。

P140，E8-2:Building large new hospital in the bistate area would constitute a wasteful use of resources, on the basis of avoidance of duplicated facilities alone.

(E) if only because the duplication of facilities should be avoided.

问题：if 和because两个连词能一块用吗？

P141，E8-6:Besudes yielding such psychological rewards as relief from stress,deep relaxation,if practiced
        regularly,can strengthen the immune system and produce a host of other physiological benefits. 

(B)one can strengthen the immune system through deep relaxation,if it is parcticed regularly

答案是A，但是我觉得deep relaxation和yielding逻辑上不对，我选了个B，就这个答案是人做主语。

P141，E8-7:直接看答案吧：developed only after Harry Truman's support of civil rights legislation bt Harry Truman,

就这个选项怎么看也不对。

我都快疯了，请各位好心人救救我。谢谢！

1、if because：如果因为。if后面状语从句的省略。

2、deep relaxation只是插入语，不是主语...

3、我见到的版本没有by harry truman的...而且其他几个错的很明显...after when的重复啊等等...

脑子有点晕，大家再看看...

首先感谢这位大虾的回答，但是2中deep relaxation如果不是主语，那这句话的主语在哪呢？谢谢！

Besudes yielding such psychological rewards as relief from stress,deep relaxation,if practiced
        regularly,can strengthen the immune system and produce a host of other physiological benefits. 

主干：除了yielding，主语deep relaxation 可以 strengthen还可以 produce。

第三个没题看不明白

LZ 应该是抄错题了，我记得开头那个次是besides，不是Besudes