When a person wants to operate this computer, ( ) the instructions first.    

A.you will have to read
B.you must read
C.you have to read
D.he has to read
出自:当代英语语法概论

完成拼图验证

按住下方滑块,将拼图拖到缺口处后松开。

拼图背景,将小拼图拖到缺口处
向右拖动滑块