A、  B、  C、  C(A)注意assist和assistant的发音类似。(B)对帮助表示感谢，与题意不符。(C)针对“是否能够帮忙处理这个软件”的提问做出了否定回答，之后又称不清楚。所以没法给予帮助。故为正确答案。

Can you cover my shift on Tuesday?
(A)Sure, it’s in the cupboard.
(B)Yes, if you could take mine on Thursday.
(C)Sorry, the cover letter is missing.

Can you assist us with this software?
(A)Yes, the assistant will attend the seminar.
(B)Thanks for helping me.
(C)Sorry, I don’t know what it is.