平行四边形有两条对称轴。[ ]
错误
One of the tourists ______ from the tour group. That was why the tour guide lost his temper.
A.kept away
B.broke away
C.took away
D.gave away
设有学生表XS(学号,课程号,成绩),用SQL语句检索每个学生的成绩总和的语句是: SELECT学号,SUM(成绩)FROM XS______。