可以 didn't use to 和use not to 现在不区别了
in front of a group这个怎么说 嗯太直白了 有点中式的感觉最好用in the public situation为什么be afraid of不用be afraid to我觉得to do 也可以 不过你要是真较真的的话这题应该用to do 这两个还是有一定区别的 be afraid of doing指担心不利于自己的事发生 ，侧重于一种结果be afraid to do 单纯的指胆小，害怕,不敢去做某事举个例子：He was afraid to walk along the banks ,as he was afraid of falling down the river.不过很少有人分得这么仔细，就好比like to do,like doing 很少有人区别一样