_________ we have been classmates for three years, she hasn’t left me much impression, so I can’t remember her after graduation.

     volleyball is her main focus, she’s also great at basketball.

．We are taught that a business letter should be written in a formal style ____ in a personal one． 

These natural parks are important for preserving animals, which would ________ risk dying out.

Do you have any idea ______ is actually going on in the classroom?