【单选题】Chitin is a homopolymer of N-acetyl-D-glucosamine units in ________ linkage. It is a primary component of cell walls in fungi, the exoskeletons of arthropods, such as crustaceans and insects, the radu...
【简答题】Traditionally, a sentence is seen as a sequence ofwords. The study of sentence formation, therefore, involves a great deal of thestudy of the word, such as the classification of words in terms of part...