Food safety is ________ important, so the government spares no efforts to prevent food pollution.

— Did you remember to give Mary the money you owed her?— Yes, I gave it to her ________ I saw her.

—You don’t see the professor from Singapore quite often, do you? —No, we only meet ______．

By the time I reach the age of sixty, I hope to be healthy enough to travel ___________ .

 I advise you not to ask him for advice, as he was not good at getting his ideas ____.