An essential relative clause provides necessary, defining information about the noun. On the other hand, non‐ essential relative clauses provide additional, non‐necessary information about the noun.

1. Relative clauses are “embedded” grammatical structures, contained inside other grammatical structures. 2. Relative clauses play a central role in English discourse. 3. Relative clause knowledge is ...

A three-dimensional model of the early human ancestor, Australopithecus afarensis, known as Lucy, on display at the Houston Museum of Natural Science. It's a scientific estimation of what Lucy may ...