拿一个长约1.5m的玻璃筒，一端封闭，另一端有开关，把金属片和小羽毛放到玻璃筒里。把玻璃筒倒立过来，观察它们下落的情况，然后把玻璃筒里的空气抽出，再把玻璃筒倒立过来，再次观察它们下落的情况，下列说法正确的是（  ）

   The centerpiece of curling(冰壶)is the curling stone. Kays of Scotland has been making curling stones since 1851, when William Kay and his sons Andrew and Thomas set up a workshop in Mauchline, Ayrshire, in southwest Scotland. Kays is still owned by the relatives of the founder, and today it is the only curling stone maker left in Scotland.
   Used in a highly competitive sport, the curling stones are made to exact standards. First, stones are sliced and then into round “cheeses”. Finally, the cheeses are shaped and polished into curling stones in a series of steps.
   Each stone must weigh 44 pounds. Each must have a maximum diameter (直径) of 36 inches. Polishing is done by hand on a wheel using water, diamond-talcum power, and felt. Finishing the stone’s “running edge” is done entirely by hand with a special kind of paper and a digital measure and magnifying glass (放大镜). Lastly, a handle(把手) is fitted into holes on the top of the stone. Stones are computer-matched into pairs. Sixteen stones----8 pairs----are needed for a game, and since curling game field usually have 6 lanes, each game field needs 96 matched stones!
   Kays is a small company, employing less than ten skilled workers. Master craftsman and co-owner James Wyllie is skilled at all phases of curling stone making and is also an enthusiastic curler, as well as active member of Mauchline’s Burns Club, which meets regularly to honor well-known Mauchline residents.

材料二:2017年4月23日,又一个“世界读书日”。在这前后,各地广泛开展了丰富多样的“书香中国”活动。河南省开展的中华传统诵读活动、青少年创客机器人大赛,将智能与阅读相给合的活动、换读一本好书,共享阅读快乐的换读活动等,吸引了广大市民和学生们的积极参与。大家以书为媒介,传递着爱心与书香,共享着智慧与文明。
据悉，你所在的学校正在开展“倡导全民阅读共建书香河南“系列宣传活动,请你参与并完成下列问题。

如图，在△ABC中，DE//BC，AD=2，AB=6，AE=3，则CE的长为(   )