This chapter presents some basic aspects of English grammar for quick reference. However, if English is not students' mother tongue, make sure students always consult a good English grammar book or a native speaker, whenever in doubt. The chapter provides definitions for some key elements of English grammar. In English, the nouns can be used with a singular verb when referring to the entity as a group, or with a plural verb when referring to the individual members. Many English verbs can combine with a preposition to form a single semantic unit: write down, look after, and run into are all examples of phrasal verbs. In English, there are three main tenses: present, past and future. A more in-depth discussion on the appropriate uses of verb tenses, together with illustrative examples, can be found in Science Research Writing for Non-Native Speakers of English by Glasman-Deal.