It’s you do today that will make a difference in your life tomorrow.
A. that
B. what
C. how
D. which
网友回答
A. that
(答案→)B. what
C. how
D. which
解析：考查强调句型中的主语从句。强调句型的基本结构：it is/was被强调成分that/who其它成分；最大的特点是it is/was…that/who…去掉，句子仍然成立。本题句子强调的是what you do today这个主语从句，what引导起这个主语从句，并在句中做宾语。句意：正是你今天所做的对你以后的生活才会产生影响。故B正确。