64.

Mixed with an equal part of water, ethylene glycol, a compound commonly used as an automotive antifreeze, is effective at temperatures as low as –30 degrees Fahrenheit华氏.

A. temperatures as low

B. temperatures so low

C. as low temperatures

D. as few

E. as little

答案是a，但是我对c没有明确的错误判断，请指教

读上去就很不顺阿 而且as的词性无论是副词还是介词都不对了阿

 c,   A is effective as at low temperature as 30 F

seems that A is as at temperature; but

a, A is effective temperature as low as 30 F

meams that temperature is as low as 30 F

open to discuss

as + adj. + as 是慣用語法, 強調中間的定語"低"; in C, as low temperature as 中變成強調temperatue.

一是慣用, 二是重心微妙的改變, 三是有多餘贅詞的感覺.  個人淺見