It is six years since the secret disaster at Jurassic Park. The dinosaurs were destroyed and the Park was closed. But now people are finding dead animals again — are they dinosaurs? Something is still alive . . .To the teacher:In addition to all the language forms of Levels One to Three, which are used again at this level of the series, the main verb forms and tenses used at Level Four are:present perfect continuous verbs, past perfect verbs, was/were going to, passive verbs (simple aspects only and with available modal verbs), conditional clauses (using the ‘second’ or ‘improbable’ or ‘hypothetical future’ conditional) and further phrasal verbs.modal verbs: should and ought to (to give advice or expressing desirability), used to (to describe past habits, states and routines), must and can't (to express (deduced) likelihood), may and might (to express, possibility or uncertainty), could (to express hypothetical ability), wquld (to express willingness) and had better (to give advice).Specific attention is paid to vocabulary development in the Vocabulary Work exercises at the end of the book. These exercises are aimed at training students to enlarge their vocabulary systematically through intelligent reading and effective use of a dictionary.