4. From the north came a freezing rain after the
snowstorm.

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).

ok i am here, i brought some cookies and some movies. do you use blu-ray cuz thats all i brought. oh, and my friend wwill be here shortly, he is going to bring some pizza too.