用所给词的适当形式填空
1. It's not easy for some students ____(get) to school.
2. Sometimes he gets up late, so he runs____ (quick) to school.
3 . Thanks for ____ (help) me so much.
4 . My uncle is sixty years old. It's his ____ (sixty) birthday today.
5 . Liu Lu ____ (cross) the river on a ropeway every day.
的最大值 和最小正周期分别是 （ ）