identify the correct tense needed to complete the following sentence.
some of the students taken an online course before, but others have not.

have

Explanation:

Some of the students have taken an online course before, but others have not.

It makes grammatical sense this way.

when connie willis was 12 years old, her mother died. in january of 2003, willis was interviewed for locus magazine. she recognized that death is a major issue in her writing, specially because the vacuous and appalling things that people tend to say in order to support you when someone you loved dies. what really saved willis was reading. books, literature, are not false. poetry tells the truth (as dickinson said: "tell al the truth but tell it slant"). it's not a escape from reality, but a nigromantic experience where whe can talk to people that exist no more. that's the definition that connie willis gives in her novel "passage": «(literature) it's the people who went before us, tapping out messages from the past, from beyond the grave, trying to tell us about life and death! ». enrique vila-matas has figured out the esence of literary experience when he said in a lecture that he intends to have his revenge against life (and death), because to write (and to read) is a form of living and a way to remember. i like in that sense the idea of not leting anything human to get lost. i feel fiction and poetry as the shapes of an ancient anger. like in the poem from dylan thomas: «do not go gentle into that good night / rage, rage against the dying of the light».

but there is another aspect that i have learned from connie willis's quote. in his famous work "danubio", the italian writer claudio magris describes literature as house removals. some messages reach us, other messages get lost in the labyrinth. those messages which are our inheritance teach us how to live and how to die, how to love and how to hate, how to laugh and how to cry. i think that tales really shape us if we listen to them. maybe through the stories we read we learn how to emphatize with others, knowing that the bells tolls for every each of us.