In your project, there have been several changes in the cost and schedule estimates and the original estimating assumptions are no longer valid. What is the estimate at complete for your project ？（）

BAC=$300,000, AC=$100,000, EV=$150,000, CPI=$1.2, ETC=$120,000.

A．$250,000

B．$220,000

C．$280,000

D．$300,000

楼梯间应能天然釆光和自然通风，并宜靠外墙设置。靠外墙设置时，楼梯间、前室及合用前室外墙上的窗口与两侧门、窗、洞口最近边缘的水平距离不应小于（）m。

A.1.0

B.2.0

C.3.0

D.不限