1.
To ~ a target means to aim at it or move towards it.
He raised the binoculars again and zeroed in on an eleventh-floor room.
= home in on
PHRASAL VERB: V P P n
2.
If you ~ a problem or subject, you give it your full attention.
Many of the other major daily newspapers have not really zeroed in on the problem...
= home in on
PHRASAL VERB: V P P n