题目内容：

ten o"clock is __for a boy of his age to stay up.
ten o"clock is _C_for a boy of his age to stay up.
A.a to late hour
B.very much late hour
C.too late an hour
D.a so late hour

优质解答

too late for sb.to do sth.是固定搭配,意思是对某人来说做什么事太晚了.
an hour是定语插入语,修饰前面的 ten o'clock,意思是10点这个时间.
整体意思是 十点对他这个年龄的男生 来说熬夜熬得太晚了.