Sometimes writers leave out words intentionally, and the meaning of the sentence is not affected. But leaving out words can occasionally cause confusion for readers or make the sentence ungrammatical. Readers need to see at a glance how the parts of a sentence are connected.
Multilingual Languages sometimes differ in the need for certain words. In particular, be alert for missing articles, verbs, subjects, or expletives. See M2, M3-a, and M3-b.