My uncle’s house in the downtown area is much smaller than ours, but it is twice ______expensive.

I ______along the street looking for a place to park when the accident______ . 

Mum, please let us, Lily and me, go to visit the new provincial museum tomorrow,        ?

He had little idea that it was getting so late, _____?

 Space exploration has been made ______ with the development of modern science and technology.