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Choose the correct answer.
1. You won"t pass the exam unless you ... harder.
a) work    b) will work    c) don"t work
2. Why ... work last Saturday?
a) had he to    b) must he  c) did he have to
3. My watch ... in the station last Saturday.
a) was robbed  b) was stolen   c) has been stolen
4. I"m sorry, she"s not here. She ... on holiday this week.
a) had been gone   b) has gone   c) has been