参考答案：B

解析：

Short-term cash flow forecasts can be constructed by projecting current daily and weekly cash flows, both expenditures and receipts, into the future. Medium-term forecasts are often based on recent average cash receipts and expenditures, but can be made using projection models that take recent trends and seasonality into account. Longer-term cash flow forecasts should explicitly include projections for capital expenditures. Cash flow is not necessarily a fixed proportion of sales. Cash needs may be higher when sales are low, as in a period prior to a seasonal increase in orders.