Read and write only the correct forms of the verbs. use the past perfect or the past perfect continuous.  1. kate (type) the letters by the time her boss came to the office.  2. they (sunbathe) for an hour when it started to rain.  3. they (swim) in the sea for 1 hour before their mum started to shout.
They had sunbathed for an hour when it started to rain
They had swum in the sea for 1 hour before their mum started to shout
2 had been sunbathing
3 had been swimming