select count(*)
from(
select sId, avg(score) avg_s
from SC 
where cId in (
    select cId
    from Course
    where cname in ('语文','数学','英语') --根据题目要求过滤
)
group by sId
having count(DISTINCT cId) = 3 --确保计算的是三门课程的平均分，排除缺考情况
)t1
where avg_s>60