Usage of "In"

1. Indicate a location or place

1.1. I am currently staying in a hotel.

1.2. My hometown is Chicago, which is in Illinois.

1.3. She looked me directly in the eyes.

2. Indicate a belief, opinion, interest, or feeling

2.1. I am in love with him.

2.2. I believe in the next life.

2.3. We are not interested in gambling.

3. Indicate a shape, color, or size:

3.1. This painting is mostly in blue.

3.2. The students stood in a circle.

3.3. This jacket comes in four different sizes.