Distinguishing Different Formulas

Examine the following structural formulas and select those pairs that satisfy the following conditions:
Be sure to enter at least two letters in each answer box, unless you select H. Do not enter superfluous characters, since they will be counted as incorrect answers.

A
C2H5CH=CHCH3
 B
(CH3)2C=CHC2H5
 C
(C2H5)2C=CH2
 D
CH3CH=C(CH3)C2H5
E
(CH3)2CHCH=CHCH3
 F
(C2H5)2C=CHCH3
 G
(CH3)2CHC(CH3)=CH2
 H
No formulas fit
this condition.

Which are identical in all respects? .........
Which are constitutional isomers? ...........
Which are capable of stereoisomerism? ..

This script written by William Reusch, Dept. of Chemistry, Michigan State University. Please send comments and corrections to whreusch@pilot.msu.edu.