30. Вставьте пропущенное слово 1) remain2) support3) hold4) maintain TotheNorthofLondon TheAldenhamCountryParkis a large and pleasant area easily reached if you are travelling north out ofLondon. It is worth visiting if you want a quick breath of fresh air and a reasonably attractive place for a brief picnic. The most important point of the park is Aldenham Reservoir. It was built in 1796 to30 ______ the water level in the river31 ______ by the newly constructedGrandUnionCanal, and more recently has been used as a reserve public water supply. Not far from there lies the busy town ofWatfordwhich can be recommended for a brief visit. And in any32 ______ much more interesting stretches of the canal are met further north. And if you make your way through the town you can visit theWatfordMuseumin the High Street which has materials on printing and paper-making on33 ______. The picture gallery has changing exhibitions of works by artists who lived or painted in the area. Another attraction of the neighbourhood is a fascinating complex of Roman buildings, the34 ______ of a great city, once the third largest centre of Roman Britain. The private houses were impressive, many of them furnished with mosaic floors. The beauty of the mosaics can hardly be described on paper, and it is best35 ______ by standing and looking for a while. The other principal Roman site to be visited is a long stretch of the city wall which36 ______ back to the 3rdcentury