A large number of students do not bother to pursue their education in higher level and this ____ the expansion of illiteracy in society.
A. leads to
B. generates
C. results from
D. causes
有向图D=(V,A),其中V={1,2,3,4,5,6},A={(1,2),(2,4),(2,5),(4,1),(4,5),(5,4),(6,3)},则D有()个强连通分量。
A. 1
B. 2
C. 3
D. 4