How can writers improve their writing?
a) apply feedback
b) write a paper in a single day
c) focus on one writing skill at a time
d) throw out all previously reviewed essays or papers

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).

to and without are prepositions, so a, b, and d are prepositional phrases. the adverb phrase is c, about the surprise.

explanation: