—Whose T-shirt is this?
—It ___________ be John's. It's ___________ small for him.
A：can't; much too
B：can't; too much
C：mustn't; too much
已知函数f（x）=|x﹣1|+|x﹣3|+|x﹣a|．
（Ⅰ）当a=1时，求不等式f（x）＜4的解集；
（Ⅱ）设函数f（x）的最小值为g（a），求g（a）的最小值．
地球自转和公转的特征，相同的是（ ）
