【单选题】Any alteration in design would mean re-setting our machines, and the cost of this would be prohibitive ____ you could place an order for more than 5,000.
【单选题】Piston rings must be used to provide the necessary seal.的正确译文是
【简答题】Robbie is furious that the newly revised rules mean he would not be qualified for any of the major aw______.
【简答题】为了保证抗坏血酸含量测定的准确度,应该注意什么?