Please check out the following sentences. Are they acceptable? <br/><br/>(1) Somebody say... / Someone say...<br/><br/>(2) Some people say...<br/><br/>(3) I learned a lesson from this experience:<br/><br/>(4) I learned something from this event:<br/><br/>(5) The disaster tells us that how the golbal warming changed the climate and threatened mankind.<br/><br/>(6) The disaster made us meditate on what we can do to save the Earth.