[Alex80]

Hi,everyone.Can you help me find any indicator or time word that make us chose one tense over the other?(Taken from a textbook)
1.Look! Somebody(drop)their wallet on the pavement.
2.John looks tired.I don't think he(sleep)very well recently.
According to the text,the answers are:
1.has dropped 2.has been sleeping
Can I say in 1,it's pps because of the verb"Look!" or the verb"drop" tends to be shorter here ? and in 2, ppc because of "recently",but it comes with both.It's really confusing.