Раскройте скобки, употребляя глаголы в Past Perfect Continuous Active.
1) They (to keep) silence for some time when somebody entered the room. 2) She (to lie) there for two hours when we found her. 3) It (to rain) hard for 3 weeks until the weather changed. 4) The four of them joined Mark, who (not, to work) for half an hour. 5) I (to stand) at the bar for 40 minutes when my acquaintance came up. 6) She (to wait) for him all the morning when he appeared? 7) My brother (to volunteer) there for a year before he entered the university?