简答题Each multiple-choice item has one correct answer.简答题Each distractor, or incorrect option, should be reasonably attractive and plausible.简答题The correct option should appear in each position (e.g. A, B, C, D or E) approximately the same number of times in a test.简答题Each option should be grammatically correct when placed in the stem.简答题TOFEL and IELTS are typical examples of proficiency tests.简答题The correct option should be approximately the same length as the distractors.简答题The length of each option in a multiple-choice item is at random.简答题Diagnostic tests are used to identify candidates’ strengths and weaknesses.简答题The difficulty of the items should be gradually decreased.简答题Each multiple-choice item could test two features at a time.