—He couldn't find his ticket anywhere.
A:dangerous
B:successful
C:careful
D:upset
①微波②光缆③蓝牙④红外线⑤电话线⑥双绞线( )
实现社会主义现代化和中华民族伟大复兴是( )
Mary isn't here at the moment. She _______ later.
下列国际单位中,属于速度单位的是( )