方位介词 — 英语词汇题

看中文提示，补全句中的方位介词（首字母已给出）。1. My English book is b________ the two desks.（在……之间）2. The basketball is u________ the chair, not on it.（在……下面）3. The teachers' desk is b________ the blackboard, so you can't see it from the door.（在……后面）4. My ruler is i________ the pencil box.（在……里面）