watashi wa tomodachi o sensei ni shoukaishimasu.

I will introduce my friend to the teacher.

Breakdown of watashi wa tomodachi o sensei ni shoukaishimasu.

• は: topic particle
• 私わたし: I
• を: direct object particle
• 友とも達だち: friend

Questions & Answers about watashi wa tomodachi o sensei ni shoukaishimasu.

What do the particles を and に do in this sentence?

• を marks the direct object, the person being introduced: 友達を = “(my) friend (as the thing being introduced).”
• に marks the recipient/target: 先生に = “to the teacher.” General pattern: XをYに紹介する = “introduce X to Y.”

If I swap the people, does the meaning flip?

Yes.

• 友達を先生に紹介します = I will introduce my friend to the teacher.
• 先生を友達に紹介します = I will introduce the teacher to my friend.
  The particles decide who is introduced to whom, not the word order.

Does the word order matter? Can I say 先生に友達を紹介します?

Yes, that order is fine and the meaning is the same. The particles keep the roles clear:

• 友達を先生に紹介します
• 先生に友達を紹介します Small nuance: items placed earlier can feel like the topic/background; the item closest to the verb can feel slightly more in focus, but there’s no change in core meaning.

Do I need to say 私は?

No. Japanese usually omits obvious subjects. 友達を先生に紹介します is the most natural neutral statement in conversation. Use 私は when you need contrast or clarity (e.g., to distinguish you from others).

Should I use 私は or 私が here?