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Can I say,

(i) After two hours, the electricity / electricity supply came (back) on. They heaved a sign of relief. They felt glad because it was back to normal. They also learnt that electricity is important in their daily life.

(ii) He learnt a lesson that electricity is important to his daily life.

(iii) He learnt about the importance of electricity in his daily life.

(iv) He learnt that it was important to use electricity (wisely) in daily life.
Comments  
Are there correct?
http://www.EnglishForward.com/English/OnThisFruitOnDurianFruit/whxld/post.htm ,

Vincent,

Like the durian and other fruit related questions, the above posted ones had been discussed and answered before if I am not mistaken. Without improving your grammar and sentence consturction,

you are likely to keep asking the same questions for some time to come, and we will be answering the same questions.
Students: We have free audio pronunciation exercises.
I can't see anything. They are all different sentences.

So, are they correct?

(i) After two hours, the electricity / electricity supply came (back) on. They heaved a sign of relief. They felt glad because it was back to normal. They also learnt that electricity is important in their daily life.

(ii) He learnt a lesson that electricity is important to his daily life.

(iii) He learnt about the importance of electricity in his daily life.

(iv) He learnt that it was important to use electricity (wisely) in daily life.
Nobody can help me anymore?