gross profit defined Alpesh Paleja, chief economist at CBI, said: "although sales have grown in the past few months, the basic trading conditions for retailers remain difficult. We expect that the pressures on households to actually pay will continue for a while, so retailers still face challenges. " There are many types of plans that can be classified according to different criteria. The main classification criteria are: importance of plan, time limit, clarity and abstraction. However, according to these classification criteria, the type of plan obtained is not independent of each other, but is closely related. For example, short - term and long-term plans, strategic plans and job plans, etc. Glasses, also known as eyeglasses or spectacles, are devices consisting of glass or hard plastic lenses mounted in a frame that holds them in front of a person's eyes, typically using a bridge over the nose and arms which rest over the ears. Glasses are typically used for vision correction, such as with reading glasses and glasses used for nearsightedness. Safety glasses provide eye protection against flying debris for construction workers or lab technicians; these glasses may have protection for the sides of the eyes as well as in the lenses. Some types of safety glasses are used to protect against visible and near-visible light or radiation. Glasses are worn for eye protection in some sports, such as squash. Glasses wearers may use a strap to prevent the glasses from falling off during movement or sports. Wearers of glasses that are used only part of the time may have the glasses attached to a cord that goes around their neck, to prevent the loss of the glasses. Western economists further point out that the main factor that leads to the difference between trading costs in markets and businesses is the incompleteness of information. Because of the incompleteness of the information. Any party of a contract will be trying to collect, information and access to what they didn't have to monitor each other's behavior, and try to constraints, and afterwards to punish in advance of each other's default behavior and so on. All these practices produce transaction costs. As a result of these practices in the market and the enterprise can take different forms, so the corresponding transaction costs is not the same, in particular, under the condition of asymmetric information, in the process of market transactions, transaction cost, as a result of these practices are often very high. Therefore, through the organizational form of enterprises, some market transactions can be internalized to eliminate or reduce the high transaction costs generated by some market exchanges. The black-tie awards ceremony was held on 15 June at the Royal Armouries in Leeds, at the centre of the country’s great east-west glass manufacturing corridor – where nine out of ten of the UK’s largest glass manufacturers have production sites. Canning's 1929 book, economics in accounting, cites the economist's view that asset values are determined by the present value of the future cash flows of assets.