题目

如下图，正方体ABCD－ABCD中，M、N分别为AB、CC的中点，P为AD上一动点， 记为异面直线PM与DN所成的角，则的集合是（     ） A、{}                B、{|≤≤}   C、{|≤≤}   D、{|≤≤} 答案：A___ is believed ___ more and more people would fly to the moon in the future.A．That, likeB．This, asC．It, thatD．Man, when