Nowadays, sending e-mails to each other has become a way _____ what they think to others.

A．many a student expresses

B．in which more than one student express

C．that most of students express

D．the majority of students expresses

根据国家领空主权原则，一国航空器（）。

A.在另一国领空享有“无害通过权”

B.在另一国领空享有“航行自由”

C.一律不得进入另一国领空

D.只有经过特许后才可进入另一国领空