.– You are not afraid of snakes, are you?

--- No, certainly not. Not rats, not flies, and ____ ants.

A．at best

B．at least

C．best of all

D．least of all

–We didn’t see Tom at the lecture yesterday.

–He _____ it. He had attended the same lecture before.

A．mustn’t attend

B．can’t have attended

C．would have not attended

D．needn’t have attended