【正确答案】According to Palmer, words are chosen for the following criteria:
   (1)most frequently used by native speakers;
   (2)all the structural words;
   (3)most useful in explaining the meaning of other less frequently used words;
   (4)words which are useful because other words can be built from them;
   This effort to introduce a scientific rationale for selecting the vocabulary content of language course represented the first attempt to establish principles of syllabus design in foreign language teaching.