______ the best efforts of the desperate mother, the powerless baby elephant seemed to have no hope of escaping, until a team of conservation workers rushed to help.

下列各句中，没有语病的一句是

Once in bed,I read for twenty minutes and then _______ the light.

Hi, Karen, the book you want will be next Monday.—Thank you very much. I’ll go and get it then.

Dutch tulips in Dafeng are so charming that _________ tourists go there and enjoy the beautiful flowers every day.