was teaching/ taugh, please help me.

  1. Miss Brown_____ us last week because our teacher was ill.
    a. teaches b. is teaching c. was teaching d. has taught
    => I choose “c”
    2.You _____ come and visit us again some time.
    a. should b. must c. need d. could
    => I choose “a”
  2. I was born in a small village _____Lantau Island.
    a. on b. for c. in d. 0
    => I choose “c-in”
  3. We went_____ a 10-day tour of central Africa.
    a. on b. for c. in d.0
    => I choose “a-on”

1 correct
2 a and b are both possible. Faulty question.
3 a is the correct answer.
4 correct