1. Passport, please.

(What is the full form of this expression?)

2. The traffic lights are composed of the red light, the green light, and the yellow light.

(Is this sentence correct? Can we use 'amber' instead of 'yellow'?)

3. Without this, you can't leave a country and enter other countries.

(In this sentence, what is the meaning of 'you can't leave a country and enter other countries'?)

1) You can't leave a country.
You can't leave enter other countries, either.

2) You can't leave a country,or you can't leave enter other countries.

(Does that mean 1) or 2)?)

1. Passport, please? <~~The full version of this is "May I see your passport, please?"

2. Traffic lights include red, yellow, and green lights.

3. Correctly written; when you cross a border between one country and another (such as between Mexico and the US), you must show your passport.

In the last two sentences "enter" and "leave" are two separate verbs, so you need a conjunction to join them.

1. You can't leave a country. You can't enter other countries, either.

2. (same as 1)

1. The full form of the expression "Passport, please" is not explicitly mentioned in the given context. However, it is likely a request made by a person of authority (such as a customs officer, immigration officer, or airport security personnel) who is asking for your passport document. The phrase is commonly used in these situations to ask for identification or travel authorization.

2. The sentence "The traffic lights are composed of the red light, the green light, and the yellow light" is grammatically correct. The primary colors used in traffic lights are red, green, and yellow (or amber), which represent different signals for stop, go, and prepare to stop respectively. In most English-speaking countries, the term "yellow" is commonly used to refer to the color in traffic lights. However, some regions may use the term "amber" instead of "yellow." So, it is possible to use "amber" instead of "yellow" depending on the local conventions.

3. The meaning of the sentence "Without this, you can't leave a country and enter other countries" is that there is a requirement or necessity for something, which is not explicitly mentioned, in order to exit one country and enter other countries. The phrase suggests that there is a document, authorization, or permission that is needed for international travel. This document could be a passport, visa, or some other form of travel document, without which one cannot legally or practically travel across international borders.