Помогите пожалуйста ответить на вопрос
the car is now the world's number one polluter. do you think it's possible  to make  it cleaner  and safer?  have you  heard  about  electric cars 

Yes I think it is possible, because our modern industry can make new investigations, which will help us to keep our environment in clean and safe atmosphere.
No I haven't heard about electric cars, but I think that there is no anything impossible to our modern researchers and scientists.