1 맛있게 드세요. masitge deuseyo
Enjoy your meal. (Lit. Please eat it deliciously.)

>> 많이 드세요. mani deuseyo
Help yourself. (Lit. Please eat a lot.)

2 잘 먹겠습니다. jal meokgetseumnida
Thank you for the food. (used before having a meal. Lit. I will eat well.)
  3 잘 먹었습니다. jal meogeotseumnida
Thank you for the food. (used after a meal. Lit. I ate well.)
 
 4 초대해 주셔서 감사합니다. chodaehae jusyeoseo kamsahamnida
Thank you for your invitation./ Thanks for the invitation.

>> 와 주셔서 감사합니다. wa jusyeoseo kamsahamnida
Thanks for coming.