It’s widely known that first aid is      important and you can save lives if the right action is taken.

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

Government officials cannot ________ accept bribes(受贿)，but in China quite a few take advantage of their power to break the rule .

After ten years abroad, he still recognized his old colleagues ________ he set foot in China．

---Have you been to the National Theatre? ---No, but I’ve         bought two tickets for the concert to be given this weekend.