题干
He goes ______ the bridge and walks ______ the post office.
A：cross; through
B：across; towards
C：through; to
D：cross; towards
答案(点此获取答案解析）
B
He goes ______ the bridge and walks ______ the post office.
A：cross; through
B：across; towards
C：through; to
D：cross; towards
中，
，沿对角线
将
折起到
的位置，且
在平面
内的射影
落在
边上，则二面角
的平面角的正弦值为( )
