He has some books on the desk, but _______ of them is on history.
A:all
B:neither
C:none
D:both
下列不属于西北地区优良牲畜的是( )
设x,y满足约束条件x≥0y≥0x-y≥-1x+y≤3,则z=x﹣2y的最大值为____
满载一船星辉,____。