While schools emphasize its usefulness-online research in class and（）polling of students, for example – a big part of the attraction is, undoubtedly, that the iPhone is cool and a hit with students.

While schools emphasize its usefulness-online research in class and（）polling of students, for example – a big part of the attraction is, undoubtedly, that the iPhone is cool and a hit with students.
A.instant
B.constant
C.distant
D.substant
正确答案：instant