问题补充：
The number of the workers in this factory300, that is to say,
it20%.
A. has increased by; has increased to
B. have increased to; have increased by
C. has increased to; has increased by
D. have increased by; have increased to
答案：
A. has increased by; has increased to
B. have increased to; have increased by
(答案→)C. has increased to; has increased by
D. have increased by; have increased to
解析：考察固定结构。Increase to增加到…表示结果；increase by…增加了…表示程度；结合句意可知C正确。句意：这家工厂的工人数量增加到了300，就是说增加了百分之20.
