Use something like these:

•He folded his arms and sat up straight. "And you suppose he had a different motive?"

•Her eyes widened. "Really?"

I also like to use this style in an ongoing conversation:

•"You're telling me that I'm fired," Jeremy muttered. His brother, the current president of the company, shook his head. "No I'm not." "Then why does it sound like it?" "I'm only suggesting that you improve the way you work around here." "I'm working just fine! I don't see you doing anything!" "Then you're fired." Jeremy stood up and walked toward the doorway. "I hated this job, anyway."

Use something like:

He folded his arms and sat up straight. "And you suppose he had a different motive?"

or

Her eyes widened. "Really?"

I also like to use this style in an ongoing conversation:

"You're telling me that I'm fired," Jeremy muttered.

His brother, the current president of the company, shook his head. "No I'm not."

"Then why does it sound like it?"

"I'm only suggesting that you improve the way you work around here."

"I'm working just fine! I don't see you doing anything!"

"Then you're fired."

Jeremy stood up and walked toward the doorway. "I hated this job, anyway."