问题
单项选择题
The last half of the 19th century ______ the steady improvement in the means of travel.
A．witnessed
B．has witnessed
C．is witnessed
D．was witnessed
答案
参考答案：A
解析：[分析] 时态用法 根据主语the last half of the nineteenth century可以判断时间为过去时，主语和谓语witness(亲眼目睹)之间是主动关系，因此A为答案。