Combine two sentences into one by using which

Question 13: Combine two sentences into one by using which: John is late for school. This made his teacher unsatisfied.
Question 14: Complete the sentence by using used to.: Lan_______(swim) when she was a child.
Question 15: Supply the correct verb form: Before Lan went to bed, she_______(finish) her homework.
Question 16: Supply the correct verb form: When he _____ (come) to the stadium, the match had already begun.