Do not be afraid为什么不加to

Do not be afraid to be weak. be afraid of 后面为什么加to do ,而不是doing? Do not be afraid to be weak,Do not too proud to be yong. 请将以下英文翻译成中文,谢谢了： Do not be afraid to fail, do not be afraid not all students take a bus to school,这句话not前为什么不加do? i was also afraid to speak in class afraid为什么不加to用不定式呢 be afraid to do 与 be afraid of 区别 be afraid to do 和 be afraid doing 的区别? be afraid of doing 和 be afraid to do 区别 be afraid to do sth be afraid of doing sth be afraid of 与be afraid to do 区别. 求英文歌,其中一句是I do not want to be your afraid,i do not want die.