They talk to each other because they are separated by a brick wall which has a small crack in it. But the crack is big enough for them to whisper through
Remind me to turn off the lights before we leave.
The verb mood of this sentence is A) IMPERATIVE
Imperative is defined as describing something of vital importance. It is an act of giving an authoritative command.
In this case, the person talking is ordering the one he or she is talking to, to remind her or him to turn off the lights before leaving.
