Tham khảo tài liệu 'the grammar book teacher course part 69', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 548 The Grammar Book If the guests should arrive early no one will be here to greet them. Should the guests arrive early no one will be here to greet them. Conditional Clause Pro-forms As Halliday and Hasan 1976 have pointed out and as we mentioned in Chapter 10 certain pro-forms can be used to replace the entire conditional clause following if so is used if the clause is affirmative not is used if the clause is negative. For example Would you like to make a class presentation f so vo unt er- 1 I If not you don t have to. J The Meaning of Conditional Sentences A Semantic Overview English conditional sentences express three different kinds of semantic relationships factual conditional relationships future or predictive conditional relationships and imaginative conditional relationships see Figure . We will discuss each of these types with its sub-types in turn. timeless Conditional Factual Figure A Semantic Hierarchy of Conditional Sentence Types time-bound Future prediciive Imaginative . subjunctive genetic habitual implicit explicit inference inference strong condition and result degrees of weakened condition or result hypothetical counterfactual present future present past Factual Conditional Sentences Factual conditional sentences are of high frequency in everyday English and yet they are overlooked altogether in many ESL EFL textbooks. Factual conditionals include four types generic habitual implicit inference and explicit inference. Generic Factual Conditionals Generic factual conditionals express relationships that are true and unchanging for example If oil is mixed with water it floats. If you boil water it vaporizes. Because of their unchanging truth value these conditionals normally take a simple present tense in both clauses. They are especially frequent in scientific writing since the sciences are often concerned with such absolute relationships. Chapter 27 Conditional Sentences 549 Habitual Factual Conditionals Habitual factual conditionals
