It was a small love letter Janet had written. The note could look like a school girl’s scrawls about her dream guy. All that was missing was a drawing of a heart with the names John and Janet written in it.
译文：它是珍妮特写的一封短小的情书。这纸条看上去有点像是一个女学生信手写写她的 梦中情人，只是没有画一颗写着约翰和珍妮特名字的红心罢了。
All that( = what) was missing 主语从句 was a drawing of a heart 系表结构作谓语 with the names John and Janet written in it.介词短语作heart的定语。