og166

166. The prime lending rate is a key rate in the econ­omy: not only are the interest rates on most loans to small and medium-sized businesses tied to the prime, but also on a growing number of consumer loans, including home equity loans.

(A)  not only are the interest rates on most loans to small and medium-sized businesses tied to the prime, but also on

(B)  tied to the prime are the interest rates not only on most loans to small and medium-sized businesses, but also on

(C)  the interest rates not only on most loans to small and medium-sized businesses are tied to the prime, but also

(D)  not only the interest rates on most loans to small and medium-sized businesses are tied to the prime, but also on

(E)  the interest rates are tied to the prime, not only on most loans to small and medium-sized businesses, but also

Key is B. no problem. The question is why there is a comma before "but also on" in B?

exactly:

not only 后面是句子太长，用逗号表示短暂停顿，这也是逗号的一个作用，没有违反任何语法规则。