In the dehydrohalogenation of alkyl halides, a strong base such as tert-butoxide usually gives the best results

Question:

In the dehydrohalogenation of alkyl halides, a strong base such as tert-butoxide usually gives the best results via the E2 mechanism.
(a) Explain why a strong base such as tert-butoxide cannot dehydrate an alcohol through the E2 mechanism.
(b) Explain why strong acid, used in the dehydration of an alcohol, is not effective in the dehydrohalogenation of an alkyl halide.