【单选题】belong s to the Beijing Hangzhou Jiangsu the Grand Canal section .
【判断题】The Grand Canal was the longest canal in the world.
【判断题】( )对于单一频率的辐射场,其电场方向和磁场方向并不总是垂直的。
【单选题】According to the author, paddling a kayak across the Grand Canal is______.
A.
an impressive and distinctive achievement
B.
an act involving risk and danger
C.
an act which is prohibited by law
D.
the most sensible solution in the particular situation
【多选题】于丹 《 感恩生命 》 一文的语言特色有哪些?( )
【判断题】( )对于单一频率的辐射场,其电场方向和磁场方向总是垂直的。
【判断题】对于单一频率的辐射场,其电场方向和磁场方向并不总是垂直的。