【单选题】下述几种发球技术中哪一种在目前比赛中运用得最为普遍?
【单选题】当物体具有对称平面时,向垂直于对称平面的投影面上进行投射所得到的图形,以对称中心线为界,一半画成剖视图,另一半画成视图,称为( )。
【单选题】The bread is __ than these cakes
【单选题】The knife with ( ) we cut the bread is very sharp.
【单选题】The bread is too small. Give him a big .
【单选题】平行投影线垂直于投影面时所得的投影,称为