Use the liquidity premium to give an explanation for why yield curves have most often been upward sloping over the past 50 years. Could a yield curve be upward sloping even if short- term rates were...

Use the liquidity premium to give an explanation for why yield curves have most often been upward sloping over the past 50 years. Could a yield curve be upward sloping even if short- term rates were expected to remain constant? If interest rates are expected to fall dramatically, under what conditions would the yield curve still be upward sloping?