Mary and her sister arent playing basktball now
what are mary and her sister doing
when are they playing basketball
who is playing basketball
marry and her sister are playing basketball now,arent they
thier children arent always making noise in the apartment
what are doing thier children 
who is making noise
their children are making noisein the apartment,arent they
they dont make experiments  in the labarotory
who makes experiments in the labarotory
where do they make experiments
they make experiments in the labarotory,dont they