I went to the classroom to close the door yesterday. But as soon as I was _______ to the classroom, I found it already _______.

A．close; closed

B．closely; closed

C．closed; closely

D．close; close

用“油膜法”可以估测分子的大小：滴入盛水培养皿中的油酸溶液所含纯油酸体积为4.0×10^-6mL，将培养皿水平放在每小格边长为1cm的方格纸上，水面上散开的油膜轮廓如图所示．该油膜面积为S= cm²，由此可以估算油酸分子直径约d= m．