If you mean Can I knit through the front leg of the loop instead of the back? the answer is no. Well, not unless you want every other row of stitches to be twisted.
Combined purling reverses the position of the stitch on the needle, so that the leading leg of the stitch is on the back instead of the front. To keep it untwisted, you must knit through the back.
If you knit through the front instead you willl notice that the stitch feels too tight, has a tendency to split, and you can see the little legs at the bottom crossing each other as you force them to twist.
If you do opt for combined style, remember that your decreases will slant the opposite direction and must be swapped. When a pattern says K2tog you should SSK and vice versa.
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