She(be) a teacher since 2002.correct the tense of the verb

has been

Explanation:

It is expressing something that started in the past and is still doing, so you use has (she is singular) and been (form of be).

they insisted that there was not enough time to learn everything.  

explanation:

if they were going to steal the answers that is simply because they insisted that there was not enough time to learn everything.  

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).