两到PREPSC句子结构求解

PREP-1 95

Unlike frogs that metamorphose from tadpoles into adults within a one-year period, mountain yellow-legged frogs of the Sierra Nevada take three to four years to reach adulthood, and so they are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter

句子去肉剩骨：

Unlike A ,B take sometime to do, and so +句子

困惑就出现在了 and so+句子

so既可以做副词( so...that, so that, so as to)

又可以作连词直接加句子表因此(so....)

so they are restricted to deeper bodies of water that do not dry up in summer or freeze solid in winter

原句中的so从逻辑意思理解应当作因此...讲,后边的that作为定语从句修饰water,因此应该为连词而不是当作副词的so...that词组

但是如果so用做了连词,前边为什么还要加一个and呢? 这个and与谁并列或平行呢?

PREP-1 93

Both the complexity of the phenomenon known as extinction and the vastness of the biosphere have prompted many scientist to call for a large increase in the number of biologists working both in the field and in laboratories to clarify the relationships among the planet's many endangered life-forms.

句子去肉剩骨：

Both A and B have prompted sb to call for sth to clarify sth

我记得以前在OG10里见过一道题, 有一个选项说两个不定式连用会产生ambiguity,为什么本题就出现了两个不定式连用呢？

第二个to clarify 的逻辑主语又是谁呢？

求高人指点

谢谢：）

先说1 95 在这里and 是连接了两个句子 后面的句子就是so ...that  that 不做定语修饰water ，water 不能够dry up

再说1 93 第二个to clarify的逻辑主语是指biologists

我有考虑过95题可能当作SO...THAT,但是一般都是SO+ADJ/ADV+THAT, 这个SO后面直接跟了句子,是SO...THAT的倒装吗?

小的不才，还是没有看出来　prompted many scientist to call for a large increase in the number of biologists working both in the field and in laboratories to clarify the relationships among the planet's many endangered life-forms.

和错误的Declining values for farm equipment and land，which farmers use as collateral to borrow against to get through the harvest season, are　going to force many lenders to tighten or deny credit this spring.

或是错误的Government distributed electronic books and computers into high schools　to use them to replace　the textbooks.　有什么区别

汗．．．．