这个句子很正确! 完整的应该是: it has been turned off since your mum's birthday party. 意思是: 它自从你妈妈的生日party后就已经被关掉了。 turn off在这里是“关掉”的意思 has been turned off就是“已经被关掉了 ” 这句是正确的,与后面的since没有关系。——————————————————————————————————如果它是指数码相机我就明白了。那么这个turned去不去都是可以的。两句话意思差不多但是有一点点区别。it has been turned off since your mum's bir...