1 . Recently it has been noticed _____ an increasing number of students are bringing smartphones to school, _____ means using smartphones reasonably has become _____ unavoidable topic for us students.

A．/; that; a

B．that; which; an

C．/; which; an

D．that; which; the

2 . I'm starting my Spring Festival vacation on Boracay Island,________ I can enjoy fresh and clean air from the sea.

A．that

B．which

C．where

D．when