单选题 The language has always changed, but the rate of change has been uneven; minor changes have slowly accumulated in every generation, but there have been period of rapid change as well. The most important of these periods occurred during the two hundred and fifty years after 1066, the year the Normans conquered England.
A. but
B. period of rapid change
C. as well
D. year the Normans

【正确答案】 B

【答案解析】[解析] 根据B项所在句的“have been”可知，这里用的是复数形式，因此应将“period of rapid change”改为“periods of rapid change”。