37. No one has come up with a better explanation of why dinosaurs ______.

_____in the mountains for a week,the two studentswere finally saved by the local police [ ]

I don’t know when _____ tomorrow. —I will call you as soon as he_____.

The naughty boys would play ______trick on______ neighbours who didn’t give them any sweets on Halloween.

Please tell me what I said just now— Sorry， Mr. Li. I __________ the birds in the tree outside the classroom.