A a
t1
1B b2
1C c2
1D d2
1B b2
12
1D d2
span
t3
1span2
1span2
1span2
12
1span2
12
1span2
12
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
span
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
1span2
span
1span2
1span2
1span2