Thursday Morning Riddle

I attach to a tractor to truck down the road;
I’m a portable classroom; blank film to unload;
I’m an ad for a movie; attached meta-code;
One who’s lagging behind; or a mobile abode.

Who am I?

UPDATE: Riddle solved by Asher. See comments for answer.

2 Responses to “Thursday Morning Riddle”

  1. Asher Says:

    TRAILER

  2. Bill Says:

    TRAILER is correct. Way to go, Asher!

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