– Is that man Mr. Green?
– It _____ be him. He has gone to Paris on business.
A:may
B:must
C:can't
D:shouldn't
中东地区在亚洲的____ 部和非洲的____ 部。
成都平原变成“天府之国”,得益于( )
一辆汽车以速度v1行驶了1/3的路程,接着以速度v2跑完了其余2/3的路程,则汽车全程的平均速度为( )