她需要高等数学的帮助，但我完全没用。

She needed help with advanced mathematics, but I was completely ___useless.

在制作自制服装方面，我完全没用。

I am absolutely ___useless when it comes to crafting homemade clothing.

尽管上了很多课，他在学习编程方面被证明完全没用。

Despite numerous lessons, he proved to be utterly ___useless at learning to code.