再请教几道语法题，谢谢（也不知道哪年的）

kamejinUID: 2123758

average world temperatures have risen on half a degree celsius since the mid-nineteenth century.

答案b

as her focus changed, the love poetry that edna st. vincent millay produced in the 1920' s increasing gave way to poetry dealing with social injustice.

答案d

同问为什么

mwhUID: 201249

第一题，on改为by，这里的意思是平均温度上升了0.5摄氏度。
第二题，这里应该用副词 increasingly修饰gave way

kamejinUID: 2123758

谢谢，
我把increaseing看成是修饰produced 的了，就觉得很奇怪