To classify the four angles of the given quadrilateral:

• Angle A (∠A) is labeled as 70°, which is acute (since an acute angle is less than 90°).
• Angle B (∠B) is labeled as 140°, which is obtuse (since an obtuse angle is between 90° and 180°).
• Angle C (∠C) is labeled as 60°, which is acute (since it's less than 90°).
• Angle D (∠D) is labeled as 90°, which is a right angle (since it's exactly 90°).

So, the classification would be:

1. ∠A: Acute
2. ∠B: Obtuse
3. ∠C: Acute
4. ∠D: Right

Would you like further details or explanations on any part of this?

Here are five related questions for deeper exploration:

1. How do you classify angles when given different degrees?
2. What is the sum of the interior angles of any quadrilateral?
3. How can you determine the type of a quadrilateral based on its angles?
4. What are some examples of quadrilaterals with different angle combinations?
5. How can adjacent angles help determine the overall shape of a polygon?

Tip: The sum of the interior angles of any quadrilateral is always 360°, which can help in cross-checking the given angles!