After users mentioned in Question I select different configurations and types of accessories, they can place an order in the system and pay for it. The system provides several types of payment methods: bank transfer, Wechat Pay and Ali pay, etc. For each order, user can select one type of payment method to pay every time. Every payment action will generate a payment record for the order. Once the order is payed successfully, the status of the order will be labeled to be "Paid", one further payment action could be performed. Otherwise, new payment action could be performed by selecting a new payment method After the order is paid successfully, the order will be send to a processional assembler to assemble the computer. One assembler (has a unique id) might service multiple orders at the same time. If the computer is assembled successfully, the computer will be delivered by a express company. If there are some problems with the configurations selected by users, the assembler will contact the user to revise the configurations. There are several collaborative express companies, but one order can only be delivered by one company. After the order is delivered to users successfully, the order is labeled to be finished. (1) Prepare a domain class diagram for order placement, order payment, computer assembling and delivery parts of the Application including classes "Order, Computer, Payment-record, Assembler, Express-company, ete" and add properties (attributes) to these classes. (15) (2) Build a state diagram for the status of an order in the system. Tips: the status should include Placed, Paying, Paid, Assembling, Assembling-blocked, Assembled, Delivering, Finished. ete". (15) (3) Configuration selecting order placement, payment, assembling and delivery are main functions of this system.Draw a use case diagram for this software. (5)