15 ! тема раскопки. оставить предложения со всеми этими словами make a discovery, date back, do researh, spare, dig, stone tools ,artefacts

The girls were playing in the house when they made a terrific discovery. 
These fossils, which date back to 1980's, were recently discovered.
The scientists are currently doing a research on how the climate change affects on agriculture.
The well was dug 900 years ago.
It is a well-known fact that stone tools precede bronze tools.Nobody expected to dig up an artefact that night.