A:1的平方根是1
B:﹣1的立方根是﹣1
C:2 是2的平方根
D:−3 是 (−3)2 的平方根
—Scientists all over the world are ______ new drugs to treat cancer.
—It will help many sick people.
已知两条直线l1:3x+4y+2=0,l2:3x+4y+m=0之间的距离为2,则m=____