A a
t1
t2
1B b2
1C c2
1D d2
1B b2
1C c2
1D d2
span
t3
t4
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2