Telegraphic speech mostly leaves out:

1. Telegraphic speech is compact, like a telegram written to save money. 2. The words dropped are closed-class or function words, such as articles and the copula. 3. Content words such as nouns and action verbs are kept. 4. So small function words are what it leaves out. **Why not the others:** Names of objects, verbs of action and words for people are content words, which telegraphic speech keeps. _Source: Wikipedia, "Telegraphic speech", section "Term in anthropology and developmental psychology" (revision 1338901968)_