Not until quite recently _____ any idea of what a guided rocket is like.

Visitors from the US have increased （ ） 8 percent since last year.

I didn’t hear （ ） because there was too much noise where I was sitting.

It is （ ） impossible to work with this noise around.

These tickets for the performance are （ ） until the end of the month．

When we have dinner very late we don’t wash up （ ） the next morning.

These tickets for the performance are （ ） until the end of the month．

We’re sure that the environment in our city （ ） greatly through our work in the near future.

We should （ ） our differences and discuss the things we have in common.

The tall tree, （ ） leaves are darker than those of the other two, is as old as grandpa.

I suppose that when I come back in ten years’ time all these old houses _____ down.

The degree （ ） you maintain your mental health may depend on certain simple environmental factors.