Example sentences of "has be known since " in BNC.
Next page| No | Sentence |
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| 1 | In fact it has been known since the late 1950s ( see for example Nature , vol. 208 , p 423 ) that Po is widely distributed in the environment , and in man , as a result of atmospheric fall-out of the decay products of natural radon-222 , with an abundance in northern temperate latitudes of about 0.06 curie per sq.km or of the order of 10 6 curies in total over the surface of the world land mass . |
| 2 | It has been known since the 1970s that the vehicles which have dramatically increased our mobility in the last 50 years have also constituted a grave danger . |
| 3 | Thermosensitive processes ( the sensitivity of court-noué to heat treatment has been known since 1921 ) together with clonal selection are the primary methods of producing so-called ‘ virus-free ’ vinestocks . |
| 4 | The site , near modern Kerma , has been known since the 1920s but the city underneath has only emerged over the last ten years . |
| 5 | One in the British Museum ( fig. 77 ) has been known since the eighteenth century and is called the Choiseul-Gouffier Apollo after a former owner . |
| 6 | Composers do not seem to have found much use for this device , though it has been known since Weber 's day . |
| 7 | On the night hemisphere much of the surface is at about 100 K. Were Mercury to keep the same face to the Sun then the night hemisphere would be close to 0 K. The higher temperature that actually exists has been known since 1962 . |