𝘾𝙝𝙤𝙤𝙨𝙚 𝙩𝙝𝙚 𝙘𝙤𝙧𝙧𝙚𝙘𝙩 𝙤𝙥𝙩𝙞𝙤𝙣.
You need to check ________ 2 hours before the flight.

• in
• to
• __
• at