Grammar Quiz

I did the Grammar Quiz on Sunday. I did this program such as Superstitions, Practice for EIKEN Fourth Grade - Part Two Preparation, Choose the Correct Indefinite Article ('a' or 'an'), Present Perfect or Past Tense, Assorted Questions – 1, Hong Kong, Canada Facts, Various Grammar Questions, To Be: Past and Present, Telephone English. I was almost got 80%, sometimes I got 100%, but I can’t get 80% in Telephone English. I don’t understand. I finished this program I knew how to use a, an, in, the, and ask question, but I want to learn tense but I cannot found them.