不同的标点符号表示不同的句子结构,代表着不同的句子关系。因此标点符号在解题中发挥重要作用。很多考题被做错全是标点惹的祸,所以我们说,小标点,大问题。第一组:(1)The book was written in 1946,____the education system haswitnessed great changes.(2)The book was written in 1946,and____the education system haswitnessed great changes.A.when B.during which C.since then D.since when答案与解析(1) D;(2) C。题(1)前后句用逗号隔开,为主从关系,排除选项C;从定语从句时态上考虑,只有since常与完成时连用,故排除选项A和B。when除用 Different punctuation marks indicate different sentence structures and represent different sentence relationships. Punctuation marks therefore play an important role in problem solving. Many test questions are done wrong punctual blame, so we say a small punctuation, a big problem. The book was written in 1946, and ____ the education system has great changes. A.when B.during which C.since then D (1) The book was written in 1946, ____ the education system haswitnessed great changes. .since when answers and parsing (1) D; (2) C. Question (1) before and after the sentence separated by commas, mainly from the relationship between the exclusion of options C; from the attributive clause temporal considerations, only since often used in conjunction with the completion, it excludes options A and B. when used