In the organic chemistry experiment, we used phthalein as an indicator.

Naphthalene is a compound often used in organic chemistry.

In this experiment, we will observe the crystallization of naphthalene.

Phthalazine is a compound often used in organic chemistry.

I'm thinking of having twice-cooked pork for dinner tonight.

My zodiac sign is Gemini.

He was born under the sign of Gemini.

They are twin brothers.

I am looking forward to the day we meet again.

Again, he started that story.