题目

Different kinds of information _____ by him in this way. A.be learned    B.is learned   C.learn   D.are learned 答案：D（本小题满分12分）如图，三棱柱中，平面平面，四边形是矩形，，分别为的中点.（1）求证：∥平面；（2）求点到平面的距离.