пронумеруйте каждый глагол-сказуемое и определите его видовременную форму и залог.
1) It increases the length of the growing season, many crops being started under cover before it is possible to grow them outside. Where the seasons are especially short this is the only means of maturing such tender long-season crops as tomatoes, peppers, eggplants, and melons. Provided the crops bear continuously, it is obvious that the early started plants may produce larger yields due to extending the length of the growing season. 2) By starting the plants under cover earlier than it is possible to start them outside, the vegetables can frequently be matured at an earlier date. 3) By growing the crops under cover for a portion of their growing season they may require less time to mature in the field. This enables the grower to grow more crops on the same land during the same season.
Various equipment is used for protecting early grown plants. Greenhouses provide the best facilities for growing early vegetables, since the temperature may be more easily controlled by better ventilating facilities. The workmen can do a much better job and they do not have to stoop down and lean over, nor will there be any danger of exposing the plants to cold temperatures, when they are watered. Hotbeds are artificially heated whereas cold frames have no other source of heat but natural or solar heat. Hotbeds are usually covered with a glass sash as glass admits a maximum of light and has some other advantages.
Cloth and some similar materials have been substituted for glass in making the cover but have proved to be less satisfactory and are but seldom used.