Dangling Modifiers

A dangling modifier is when the meaning of a sentence is left "dangling" to mean something else because something is left out.

Examples:

• Reaching the heart, a bypass was performed on the severely blocked arteries. 
• Reaching the heart, the surgeon performed a bypass on the severely blocked arteries. 
• The second one is correct, because the person performing the action is named in the subject of the sentence so the opening phrase doesn't dangle.  

• Determined to learn to read, Wanda was delighted to discover that there was an adult literacy program in her apartment building.  
• Determined to learn to read, an adult literacy program in Wanda's apartment was just what she had been looking for. 
• The first one is correct, because the subject of the sentence names the actor.