provision for quantity contingencies in any particular item or class of work with a high expectation of quantity overrun should be made by entering specific "provisional quantities" or "provisional items"in the bill of quantities for the item or class of work in question,and not by increasing the quantities for that item or class of work beyond those of the work normally expected to be required.
參考答案:这是一个具有法律色彩的句子，意思是：
对于那些对质量要求普遍很高的工种或具体工作项目，必须采取预防措施来应对可能发生的质量问题。方法是在有关的工种或项目数量单中填写具体的“临时数量”或“临时项目”，而不是将该工种或具体工作项目的数量增加到超出正常工作所要求的水平。