Chia dạng đúng của từ trong ngoặc

3. they were surfing the internet . they saw calls for joining programmes to save endangered species ( Uwhile ) =>................. ; 4. I Uwent on holiday with two of my friends ( mine ) -> I went .......................... ; 5. " why do people call Mars the red planet?" linh asked me .-> linh asked me................... ; 6. A serious road accient happened . we were waiting for the bus yesterday ( Uwhile ) ......................... ; 7. It started raining . they were putting up the tent ( when ) =>.......................