1. Jack (arrived/has arrived) . He's in the living room. 2. Look at the colour of the water! Something (polluted/has polluted) the river. 3. Scientists (have invented/invented) the digital camera in 1991. 4. We (saw/ 've seen) ...

1. Jack (arrived/has arrived) . He's in the living room. 2. Look at the colour of the water! Something (polluted/has polluted) the river. 3. Scientists (have invented/invented) the digital camera in 1991. 4. We (saw/ 've seen) the new Johnny Depp film last night. 5. Why isn't my mobile wotking? - I don't know. I (haven't touched/didn't touch) it. 6.(Did you finish/Have you finished) the washing up? Shall we play cards now?