1 B2 慣用的 ニュートラル
特にいくつかをしぼった後で、一つのことに全力で注意や努力を向ける
"After weeks of investigation, detectives finally zeroed in on the most likely suspect."
“
We need to zero in on the issues that matter most to working families.
— Common political speech phrasing, widely attributed to various US politicians including Bill Clinton
分離不可