It is necessary to (no subject): cần + verb

In recommendations, guidelines and reports, cần often starts a sentence with no subject at all: Cần tăng cường kiểm tra an toàn thực phẩm (food safety inspections need to be stepped up). English uses "should be" or "it is necessary to"; Vietnamese simply leaves out who does it, because the reader knows it's whoever is responsible.

You'll see it in the conclusions of papers, in official guidance, and in lists of tasks, one item per line: Cần rà soát …, Cần bố trí …. Health news uses it to advise the public: Cần đưa trẻ đi khám ngay khi sốt cao. Leaders' speeches use it to set tasks.

Two fixed openers point the reader to something important: Cần lưu ý (rằng) … (it should be noted that …) and Cần nhấn mạnh (rằng) … (it must be stressed that …). Both are common in papers and in tax or legal guidance. Không cần works the same way: Không cần nộp bản sao công chứng (no certified copy is needed).

In everyday speech, cần has a person in front: Em cần nghỉ ngơi (you need rest). Without a subject it sounds like a notice or a report, so in conversation say who: Mình phải kiểm tra lại (we need to check again).