设f(x)在[a，b]上连续，在(a，b)内可导，0＜a＜b．试证明：存在ξ∈(a，b)使
参考答案：[证明]
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--What are you doing now?
-- I’m talking to Mary online. She ___ from Canada a few days ago.
A．is coming back
B．come back
C．came back
D．went back
连词成句。
1. is A faster train than bus a
2. take we May train the
3. cab a A is than slower bus
4. do we When leave
