3. The following constants cannot be used as constants

a.0xA5

b.2.5e-2

c.3e2

D. 0583// Octal number is 0~7.

4. The following options are correct integer constants:

A. 1.2 // Non-integer constant

b.–20

c. 1，000

d.6 7 4

5. The following options are not correct real constants:

a.3.8E- 1

b.0.4e 2

C.–43.5//Non-real constant

d.243.43e-2