day by day, day after day
day by day意为“一天天地”，指每天重复做一件事，含有逐渐转变的意味，在句中常作状语；day after day意为“一天又一天”，指连续的日子，意味着时间长久，在句中可作宾语、状语等。如：
Day by day he seems to grow a little stronger. 他渐渐地变得强壮起来。
The situation is improving day by day. 形势一天天好转。
We waited day after day, but the visitor never arrived. 我们等了一天又一天，但客人还没到来。
I have to do this work day after day. 我日复一日地做这件工作。
month by month, month after month和year by year, year after year等用法相同。
decide, determine, make up one’s mind
decide的意思是“决定”，指经过考虑或讨论研究，打定主意，结束踌躇、疑惑、争论等状况。如：
It has been decided that the meeting shall be put off. 经决定会议延期举行。
In the end she decided to join the army. 最后她决定要参军。
determine表示“决定，决心”时，指经过认真考虑之后下定决心。如：
We determined on an early start. 我们决定尽早出发。
We are determined to win the game. 我们一定要赢这比赛。
make up one’s mind的意思也是“决定，决心”，是和犹豫不决相对的用语，意即打定主意。如：
I have made up my mind to study English well. 我决心学好英语。
