‘Whenever‘は’every time‘ の代わりに使うことができます。日本語の「～する時はいつも、毎回」にあたります。
例えば・・・
Whenever the sun shines, the English get in their cars and head for the beaches.
= Every time the sun shines, the English get in their cars and head for the beaches.
= Every time the sun shines, the English get in their cars and head for the beaches.
しかし ‘whenever‘ は、上記とは別に会話の中で、何か物事が起こるのが何時でも構わない時にも使います。
例えば・・・
“When do you want to have your hair cut?” “Whenever.”
“When shall we go out?” “ Every time you like.”
“When shall we go out?” “ Every time you like.”