I am not sure how long they _.

I am not sure how long they _. --How long are they _______the house?--I am not sure.A.buyin I an not sure how long they____ by the way,how long ______?I am not sure .I hope to see all i am not sure if they're coming什么意思? I am sure they do not get there by chance. Er...i am not sure. I am not sure是什么意思 I AM NOT SURE YET? I am not sure how to put this,but I broke your cup. I'm sure I am not wrong i am not sure how mum will feel when she gets my present ,bu