友
I write it.
私は書きます
I write a letter to my friend.
私は友に手紙を書きます
I write a letter to my friend in the study.
私は書斎で友に手紙を書きます
I write a letter to my friend in the study tonight.
私は今夜、書斎で友に手紙を書きます
I write a letter to my friend in the study with my younger brother tonight.
私は弟と今夜、書斎で友に手紙を書きます