However weak we are，we can still do something against the powerful nature so long as we are     prepared．

When you cross the street, you can never be _______ careful.

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

---Laura calls on her teacher pretty ____, doesn’t she? ---Yes. At least three times every week.

When Helen saw her tutor nod ______ to her, she calmed down and went on with her performance .