K2Tog Knit to required place, insert RH needle knitwise through next 2 sts, knit them as 1 st.

SSK Insert RH needle into the next st k-wise, then slip it onto the RH needles without knitting it.

Insert the RH needles into the next st p-wise, then slip onto the RH needle. You have slipped sts on the RH needle, 1 slipped K-wise, 1 slipped p-wise.

Insert the tip of the LH needle from left to right up into the front of the two slipped sts (the RH needle is behind the LH needle). Knit these two sts tog.

CDD Insert RH needle from front to back into next 2 sts on LH needle. Slip these two sts k-wise tog onto RH needle without knitting them.

Knit the next st on LH needle. Note that the two slipped sts are sitting unworked behind the st you have just knitted

Insert the tip of the LH needle from left to right into the front of the two slipped sts and lift the two slipped sts over the knitted st.