1.7 people stand in a row without restriction. Need to consider the arrangement order, that is, arrange 7 people at random. This method of standing is 7 people =7! =5040 species.

2. The tallest Gao Xiao can't stand on both sides, so he has five different standing postures in the middle five positions, and then the remaining six positions are randomly arranged, that is, the arrangement of six people =6! This kind of * * * standing method = 5x6! =3600 species.

3. The tallest Gao Xiao is standing in the middle, so he has only one standing method, and the other six positions are randomly arranged, so this * * * standing method =6! =720 species.