Patrick Hofer/Getty Images
Why do some flowers close up at night but others stay open?
Steve Child
Glossop, Derbyshire, UK
Huguette Roe/Shutterstock
Is it more environmentally friendly to keep my 23-year-old petrol car or to scrap it and buy a new electric one? I drive about 8000 kilometres a year and am quite old, so my car may outlast me.
Ian Burton,
Hemel Hempstead, Hertfordshire, UK
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