Explanation

The mobile phone is a recent invention, which can be as annoying, as it is useful.

موبائل فون ایک حالیہ ایجاد ہے ، جو اتنا ہی پریشان کن ہوسکتا ہے ، جیسا کہ یہ کارآمد ہے۔

"Which" is used to refer to objects, like "mobile phone," and adds non-essential information to the sentence.