__ the difficult maths problem, I have consulted Professor Russell several times.

It took _______ building supplies to construct these energy-saving houses. It took brains, too.

walking in the Shanghai World Expo for a whole day, my legs ____ under me and I couldn’t walk any farther.

I don’t like this pair of glasses. Could you show me —OK. Here you are.

We met an old friend in New York ____our expectationShe waved at us ____ the street when she saw us