2、A；

3、A；

4、B；

5、B；

6 、( 1)≈2 =≈4(2)≈b+≈BAD = 180

7. It is known that the definition of the angular bisector is known that ∠3=∠2, the internal dislocation angles are equal and the two straight lines are parallel.

8、C；

9、A；

10, AB parallel CD is equal to the inside angle of the side, and the two straight lines are parallel.

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