ABCD is a quadrilateral in which `/_A= 60^(@), /_ B= 70^(@), /_ C =110^(@)` and `/_ D =120^(@)`. The number of pairs of parallel lines is `"________________"`.

Answer

To determine the number of pairs of parallel lines in the quadrilateral ABCD, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Angles:**
We have the following angles in the quadrilateral:
- Angle A = 60°
- Angle B = 70°
- Angle C = 110°
- Angle D = 120°

2. **Check for Parallel Lines:**
According to the properties of parallel lines, if two angles on the same side of a transversal sum up to 180°, then the lines are parallel.

3. **Calculate the Sums of Angle Pairs:**
We will check the following pairs of angles:
- Pair 1: Angle A + Angle B = 60° + 70° = 130° (not parallel)
- Pair 2: Angle B + Angle C = 70° + 110° = 180° (parallel)
- Pair 3: Angle C + Angle D = 110° + 120° = 230° (not parallel)
- Pair 4: Angle D + Angle A = 120° + 60° = 180° (parallel)

4. **Identify Parallel Lines:**
From the calculations:
- Angles A and B do not form a pair of parallel lines.
- Angles B and C form one pair of parallel lines.
- Angles C and D do not form a pair of parallel lines.
- Angles D and A form another pair of parallel lines.

5. **Count the Pairs of Parallel Lines:**
We found two pairs of angles that sum to 180°:
- Pair 1: Angles B and C
- Pair 2: Angles D and A

6. **Conclusion:**
Therefore, the number of pairs of parallel lines in quadrilateral ABCD is **2**.

### Final Answer:
The number of pairs of parallel lines is **2**.