1) Despite his high IQ, he often came across as dull-brained due to his lack of common sense.

2) The student's dull-brained approach to problem-solving hindered her progress in the class.

3) The detective quickly dismissed the dull-brained suspect as not being capable of planning a crime.

4) His dull-brained response to the situation left everyone wondering if he understood what was happening.

5) The manager found it frustrating to work with dull-brained employees who needed constant guidance.

6) The dull-brained decision to cut costs without considering the consequences led to a major loss for the company.

7) The dull-brained character in the movie provided comic relief with his obliviousness to what was going on around him.

8) Her dull-brained comments during the meeting made it clear that she hadn't been paying attention.

9) The teacher struggled to engage the dull-brained student in class discussions.

10) His dull-brained approach to investing resulted in significant financial losses.