what is the formula to calculate gross profit Keynes argued that savings and investment were two interdependent variables, not two independent variables. The response to the value of diversity is intellectual. Intellectual (including concept and image) is higher animals of conditioned reflex formed on the basis of more common, more abstract conditioned reflex, it is produced by the external and internal relations of things contact of abstract understanding. Among them, the abstract cognition of the internal relation of things forms the concept, and the abstract understanding of the external relations of things forms an image. Concept and image is what you have done to learn something from the induction and summary, make the person's behavior pattern has a more systemic and purpose, make people not only can adapt to the complex survival environment, but also the initiative to choose the environment. Due to the learning of thinking and behavior patterns are often fragmentary, irregular and blind, people often "learning, and I don't know why," can't consciously use, only after forming concept and image, will be to sort out a "main line", and according to the logic of determined by the "mainline" direction will learn things lined up. Through the abstract and image, the person can be either things to take the same responses to different stimuli, can also take different responses of the same stimulus thing, make the person's reaction mode diversification, flexible and purpose. For example, there are also harmful substances, which can be used in various ways, such as evasion, attack or protection, depending on the situation. Anyway, intellectual is very higher organisms (such as monkeys and apes) outside of the value of diversity things very advanced way of ordering reac It is worth mentioning that Surface Pro is by far the most popular with users of Surface equipment, Surface Pro 4 proportion is as high as 39.7%, Surface Pro 3 also is as high as 21.7%, while older equipment Surface Pro/Pro 2 still has 5.6% and 3.7% of the users. On the Surface Book, however, the average user accounts for just 0.4 per cent of the market, except for the 7.5 per cent share of the first generation, which may be due to a short listing. 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. "