1.as acts as a relative pronoun to guide non-restrictive attributive clauses, which can be placed at the beginning, middle and end of a sentence.

As refers to the whole sentence, which is an parenthesis and is used as subject, object or predicative in a clause.

2.as...as means "same", which means to compare at the same level. Note that the first as is an adverb and the second as is a conjunction. Its basic structure is as+

adj

adverb

+as. The second as leading adverbial clause is an ellipsis. The complete form is as follows:

we

must

rescue

be like

many

water

be like

we

can

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