“两条直线相交成直角,就叫做两条直线互相垂直.”这个语句是( )
A.定义
B.命题
C.公理
D.定理
两条直线相交成直角,就叫做两条直线互相垂直,这是垂直的定义.
故选A.
On June 11th, 2013, Shenzhou-10 carrying three astronauts into space from the space center in Jiuquan. All the Chinese people are proud of its successful launch.
A. sent up B. are sent up C. was sent up
贯流锅炉和一般锅壳式内燃锅炉一样没有集箱。()