to to 还是 for for
看看这道题，是填 to to 还是 for for：
Who is it up _________ decide whether to go or not？
A. to to B. for for C. to for D. for to
许多同学一看选项排除了A和B，因为像两个介词连在一起用一般是不可能的。至于C和D，该选哪个呢？显然空格的 decide 是动词，所以它前面应是不定式符号to，而不能是介词 for，所以此题应选D。此分析尽管有些道理，但所选答案还是错了，正确的选项应是A。同学们应该熟悉 up to 的用法，它的意思很多，其中一个用法是表示“该由……负责”，“在于……”、“取决于……”。如：
“Shall we go out?” “It’s up to you.” “我们出去吗？”“这由你决定。”
When we start is up to you. 我们什么时候出发由你来定。
It’s up to you to decide whether to go or not. 去还是不去由你来决定。
Who is it up to to decide whether to go or not？
(1) I asked him what he hoped _________ his birthday.
A. on on B. at at C. to to D. for for
答案选D。比较：He hoped for a bike for his birthday. 若对其中的 a bike 提问即得到 What did he hope for for his birthday.
(2) Would you tell me what subject you were good _________ school?
A. at at B. in in C. for for D. with with
答案选A，be good at = 擅长于，at school = 在校，在学校读书。
(3) The books we _________ nothing to do with this subject.
A. have have B. do do C. read read D. need need
答案选A，we have 是修饰 the books 的定语从句，have nothing to do with 是短语，意为“与……无关”。
(4) Whoever has a strong _________ not leave his work half way done.
A. shall shall B. will will C. can can D. may may
答案选B, 第一个will 是名词，意为“意志”，have a strong will 意为“意志坚强”；第二个 will 是助动词，意为“将”。