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? c. Which tense refers to something which happened before something else? Key: a. past simple b. past continuous c. past perfect ? Complete the passage in exercise 4 with the correct form of the verbs. Key: (1) had done (2) was waiting (3) had seen (4) had asked (5) was crying (6) left (7) ran (8) was talking (9) had finished (10) did (11) knew (12) had happened (13) had fotten (14) took (15) had frozen 1. “I visited China last year.” “That ______________