mostly sell them

[azz]

Can one say

a. I mostly sell the books I buy and read, but I sometimes give them away for free.
b. Mostly I sell the books I buy and read, but I sometimes give them away for free.

Many thanks.

 

[Rover_KE]

a is better, but 'for free' is redundant.

 

[teechar]

If you're going to use "b", put a comma after "mostly."

 

[emsr2d2]

Also, if you're going to use b), I'd use the same word order in the second half as the first.

Mostly, I sell the books I buy and read but sometimes, I give them away.

I prefer "usually" and "normally" to "mostly" but yours isn't wrong. In everyday conversation, I'd actually say "I usually sell books after I've read them but sometimes I give them away".