Select the most appropriate option to fill in the blank.

The entry gates were closed ______ we could enter in.

before

The most appropriate option to fill in the blank is: before

Here's why:

• "Before" indicates that the closing of the gates happened prior to the attempt to enter. This aligns with the situation where the closed gates prevent entry.
• "Till" and "until" both suggest waiting until a certain point. In this context, it wouldn't make sense to wait for the gates to close to try to enter.
• "After" suggests the gates were closed after the attempt to enter, which contradicts the idea that the closed gates prevented entry.

Therefore, "before" creates the clearest cause-and-effect relationship between the closed gates and the inability to enter.