变性蛋白质的特点是

A．粘度下降
B．溶解度增加
C．颜色反应减弱
D．丧失原有的生物学活性
E．不易被胃蛋白酶水解

Darth Corporation’s most recent income statement shows net sales of $ 6000, and Darth’s marginal tax rate is 40 percent. The total expenses reported were $ 3200, all of which were paid in cash. In addition, depreciation expense was reported at $ 800. A further examination of the most recent balance sheets reveals that accounts receivable during that period increased by $1000. The cash flow from operating activities reported by Darth should be:

A．

B．

C．