Omitting verbs in comparisons

[skumar94]

I came accross this sentence in MGMAT strategy guide 8th Ed. Pg 129.
I walk as fast now as [I walked] when I was younger.
As per the book this form is correct without the clause I walked as it is understood and logical.
However in OG 12,explanation to question 87,Pg 728.
In an effort to reduce......
the explanation mentions that the second verb should be correctly conjugated with the first verb "sell".Further OG rejects option B because it requires "sold" to be used as a second verb.

Therefore, I am curious that if as per OG this logic is correct then what makes walked correct in the MGMAT sentence? or am I missing something?

[tim]

i think in the strategy guide example, the understood "i walked" is unnecessary and potentially misleading. the comparison here is between now and when i was younger. as such, we don't need the verb at all. this is very different from OG12 problem 87, where the comparison is very clearly between the verbs..