Ms Stephens continues: “The new extension has provided a fantastic and really flexible space that thanks to the new PURe® patio doors and windows, can be enjoyed whatever the weather. It’s great to be able to open up the living space and enjoy the close access we now have to the garden but even when the blustery weather that we are so familiar with here in the Yorkshire Dales takes hold, the glazing has provided us with a peaceful and cosy retreat. It’s the perfect space for both work and relaxation and I couldn’t be happier!” Study calculus, the first step is to understand that the "limit" the necessity of introducing: because, the concept of algebra is people are familiar with, but, algebra is unable to process the concept of "unlimited". So in order to use algebraic processing to represent infinite quantities, the concept of "limit" is constructed. In the definition of "limit", we can see that this concept bypasses the problem of dividing a number by 0, and introduces a process with any small amount. Is to say, the divisor is not zero, so meaningful, at the same time, this process can take any small small, as long as meet the Δ range, less than the arbitrary small, we can say he limit to the number, you can think it is opportunistic, however, his practical proof, such a definition is more perfect, the possibility of giving the correct inference. The concept is successful