BD try to do sth
C recover from sea
E recovering...... to try to do do 和做的内容重复了

idiom：try to do not try for doing
recover out of 不好
C：trying 这件事很worthwhile？

"this process" = "trying to recover uranium out of seawater"
However, "trying to ..." cannot be said to be expensive. We can say "to recover ..." is an expensive process, but we cannot say "trying to recover ..." is an expensive process. So (C) is illogical.

个人拙见：from与out of 均表示来源或出处。但是from 注重起点，译为“从„„” 例如：he shouting of the soldiers'drilling could be heard from the playground
out of out of 侧重于从里向外，译为“从„„里出来” 例如：We are moving out of our flat.
所以此处，是不是 from 比 out of 合理

尽量避免用to try to....或者 trying to ...之类的结构做主语

"this process" = "trying to recover uranium out of seawater"
However, "trying to ..." cannot be said to be expensive. We can say "to recover ..." is an expensive process, but we cannot say "trying to recover ..." is an expensive process. So (C) is illogical.

BCD都有硬伤可以排除，E则是因为对仗问题，to try to ...和 Recovering...不对应，而且to try to do显得十分冗杂，A的表述清晰简洁。It 做形式主语未必就错，要注意

the idiom is "to try to do" not try for doing or try and do
recovery from not recovery out of

B to try and recover 错误，应该为try to recover ;
c recover...out of... 错误
e recovering 和 to try to do 的do重复

B:some day放句首影响时态---but后面的句子的时态和前面句子时态不一样，是并列关系。
C:trying to do xxx is worthwhile的说法有误，细微改变原文句意，应该是doing xxx is worthwhile。
D：to try for xxx强调名词，错误
E：doing sth is worthwhile to try就可以，不用再加to do,语义重复
另：recover A from B是固定搭配

recover out of 不对

B: 没有并列关系
C: trying (to do sth) may be worthwhile 试图这件动作不是worthwhile的
D: sth may be worthwhile to try (to do 多余）

B: try and recover
C: *uranium out of seawater* is wrong, suggesting that uranium, in big volumes, is kept in sea and it just need to be taken out from the sea. But actually uranium is processed out.
D: try for
E: *Recovering ... try to do* (redundant)

A:
B：try and recover并列错误
C: out of seawater搭配不对
D:to try当主语不如形式主语It 好
E:to do多余

B: try and recover 不对
C&D: recover out of 不对
E: to try to do -->to try to do recovering，不对

1. idioms: try to do. b中try and recover逻辑上不平行，try uranium?不对，排除b。d中try for也不对，排除d
2. idioms: recover from. not "recover out of",排除c/d
剩下a/e, e中worthwhile to try就可以了，后面的to do有点redundant. sth may be worthwhile to try. try后面的宾语又是该句的主语，这就变成了“sth may be worthwhile to try sth“--> redundant.
最后剩下a.

Trying to recover uranium out of seawater主语过长，应该用形式主语it代替更好。然后可能是根据答案强推的。。。but后面强调的是“at present”这个时间，前面最好有个差不多意思的词跟它并列

the idiom is "to try to do" not try for doing or try and do