There are a small number of people involved,possibly ________ twenty.(2013·江西,26)
It was along the Mississippi River _________ Mark Twain spent much of his childhood.
It is a fact that _________ differences between countries may cause misunderstandings in communication.
North Europe __________ Norway, Sweden, Denmark, Finland and Iceland.
I was greatly impressed __________ the speech by the mayor of Shanghai before the final voting for EXPO 2010.
When I entered the step-classroom (阶梯教室), the lecture __________ and the audience __________ attentively.