【完成句子】In Britain, robot sales appropriately peaked in 1984, but have been declining ever since. This is partly because, British wage rates are too low to make robots financially attractive and partly because engineers now have more experience with robots and are more aware of the difficulties of introducing them effectively.Robots are less popular in Britain today partly because __________.
A、too much energy
B、based on American designs
C、they are too costly
D、they are not reliable
【正确答案】：C
【题目解析】：本段第二句就是讲的两个原因，即人们的工资水平太低，也就是没有能力使机器人发挥出创造财富的作用，言下之意就是成本高。第二个原因就是人们逐渐意识到了操纵机器人不是件容易的事情，所以使用率就下降了。所以应该选C。
