有一个焦距为15cm的凸透镜，要想用它成缩小的实像，物距应____cm；若用它作放大镜观察地图，该凸透镜与地图的距离应____cm。
大于30；小于15
补全对话。
A: I want _____________ put this table _____________ there. But it's _____________ heavy.
Could you _____________ me?
B: _____________! _____________ do you want to put it?
A: Under the tree.
B: _____________.
A: Please _____________ a bottle of orange.
B: _____________ you.
A: Would you like another one?
B: No. _____________.
防水混凝土拆模后及时进行回填土，以利于混凝土前期强度的增长及获得预期的抗渗性能。( )
