The number of the workers in this small company has grown 1000 to 1200．This means it has risen _______ 20 percent．

A.by

B.at

C.to

D.with

答案及解析： A

解析：

表达“变化了多少”用介词by。to表示“变化到某个程度”, 如：The number of the employees has risen to 1200。这道题说明的是增长了20％, 显然, 答案是by。其他介词均没有这种用法。正确答案是A项。