It is rather ______ that we still do not know how many species there are in the world today.

The scientist corresponds with colleagues in order to learn about matters ______ to her own research.

It took________supplies to construct these energy­saving houses. It took brain too.

There is a lot__________ to discover in these places. Every week we find new things

If you want to book tickets for a film in Qionghai, just call 62838009. It _______be simpler.