下列哪个语句实现将计算机系学生各科成绩置为0（）
A. update sc set grade=0 where sc.sno=student.sno and sdept= ’ cs ’
B. update scset grade =0 where sno in(select sno from student where sdept=’ cs’ )
C. update grade=0 from sc where sno in(select sno from student where sdept= ’ cs ’ )
D. update grade=0 from sc where sdept= ’ cs ’
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