Question

单句改错：1,All but was here just now.2,Although he is considered a great writer ,however his works

Answer 1

1.all 指代物的话用单数，如果指代人的话实用复数。前面指代的应该是人吧，你自己看下前文哦，那么就把was改成were.
2.划掉however,应为although 和however 不能联用。