隋朝大运河的开通产生了怎样的作用?
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大大促进了我国南北经济的交流。(意思对即可)
There _____ still some milk in the fridge. It's not necessary to go to the store today.[ ]
A. am
B. is
C. are
D. be
哪一个卡环为Ⅱ型卡环()
A.隙卡
B.倒钩卡环
C.圈形卡环
D.三臂卡环
E.回力卡环