1 I (cry) when mother used to take me to school. (past habit)
  2 Students (not be) too concerned about making mistakes when speaking. (mild obligation)
  3 He got an A in Maths. He (be) very bright. (logical conclusion)
  4 You (be) crazy to spend so much money on your wife’s engagement ring. (logical conclusion past)
  5 Income taxes (be) paid promptly to avoid fines being incurred. (Strong obligation)
  6 Manchester United (overcome) their shortage of one player and win the game. (ability past)
  7 Several years ago, people (carry) water with them through customs. (past ability)
  8 They left home about an hour ago so they (arrive) by now. (past mild prediction)
  9 Before 1972, people (take) boats to travel between Hong Kong island and Kowloon. (Past strong obligation)
  10 Many people believe that Hong Kong (not thrive) if the British colonial power had remained in place after 1997. (past prediction)