Only in this way to make improvement in the operating system. A. you can hope B. you did hope C. can you hope D. did you hope 答案:C 本题中“only+介词短语”置于句首作状语,须用倒装语序;因为句意表达的是一种条件,故使用did不合题意 糖元、核酸和淀粉酶的基本单位分别是A.碱基、单糖、氨基酸B.葡萄糖、碱基、氨基酸C.葡萄糖、核苷酸、氨基酸D.乳酸、核苷酸、葡萄糖