Which sentence sounds most natural in formal written English?

Should you require further assistance, please do not hesitate to contact us.

If you would be requiring more help, do not be hesitating to contact us.

In the case you require more assistance, please do not hesitate for contacting us.

Would you require assistance further, please be not hesitating.

To take something with a pinch of salt means to ___

treat it with a degree of scepticism

English Level Test: Find Your CEFR Level (A1-C2)

How good is your English, really? This 20-question placement test maps your level onto the CEFR scale (A1 to C2) — the standard used by language schools, universities and employers worldwide.

The questions get harder as you go: grammar, vocabulary, phrasal verbs and register. It takes about 5 minutes. You will get your level, what you can already do at it, and exactly what to work on next.