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Replace the infinitives by the Past Perfect, the Past Perfect Continuous or the Past Indefinite as required.
I. They (to drive) in the car for many hours before they (to come) to the crossroads. 2. The scientists (to carry) out dozens of experiments before they (to achieve) satisfactory results. 3. The violinist (to practice) the passage hour after hour until he (to master) it at last. 4. At last the postman (to bring) the letter which I (to expect) several weeks. 5. He told me he (not to see) much of her since he (to move) to another place. 6.When I (to arrive) he (to stay) at the same hotel where we first (to meet). He (to tell) me he (to wait) for me for some time already. 7. He (to consult) his watch nervously several times before he (to see) her at the end of the platform. 8. He (to write) and (to tear) up more than one letter when at last he (to find) the necessary form of address. 9. My watch (to keep) good time before I (to drop) it. 10. At the end of the week the fishermen (to think) they (to sail) long enough to reach the shore, and as there (to be) no land in sight, they (to understand) that they (to lose) their course and (to follow) the wrong route. 11. It (not to rain) for more than two months, and the fruits (to fall) before they (to become) ripe, when one August night the people (to be roused) by the sound of heavy drops beating against the roofs and windowpanes. With the rain there (to come) hope.

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I. They HAD BEEN DRIVING in the car for many hours before they CAME (to come) to the crossroads. 2. The scientists HAD CARRIED (to carry) out dozens of experiments before they ACHIEVED (to achieve) satisfactory results. 3. The violinist HAD BEEN PRACTISING the passage hour after hour until he MASTERED (to master) it at last. 4. At last the postman BROUGHT (to bring) the letter which I HAD BEEN EXPECTING (to expect) several weeks. 5. He told me he HADN'T SEEN (not to see) much of her since he MOVED (to move) to another place. 6.When I ARRIVED (to arrive) he STAYED (to stay) at the same hotel where we first HAD MET (to meet). He TOLD (to tell) me he HAD BEEN WAITING (to wait) for me for some time already. 7. He HAD CONSULTED (to consult) his watch nervously several times before he SAW (to see) her at the end of the platform. 8. He HAD WRITTEN (to write) and HAD TORN (to tear) up more than one letter when at last he FOUND (to find) the necessary form of address. 9. My watch HAD KEPT (to keep) good time before I DROPPED (to drop) it. 10. At the end of the week the fishermen THOUGHT (to think) they HAD BEEN SAILING (to sail) long enough to reach the shore, and as there WAS (to be) no land in sight, they UNDERSTOOD (to understand) that they HAD LOST (to lose) their course and HAD FOLLOWED (to follow) the wrong route. 11. It HADN'T RAINED (not to rain) for more than two months, and the fruits HAD FALLEN (to fall) before they BECAME (to become) ripe, when one August night the people WERE ROUSED (to be roused) by the sound of heavy drops beating against the roofs and windowpanes. With the rain there CAME (to come) hope.