The mobile phone is useful to us and we can use it others at any place.A. call B. calling

问题补充：

The mobile phone is useful to us, and we can use it others at any place.

A. call B. calling C. to call

答案：

解析：句意:手机对我们是有用的，我们可以随时随地能够用它。be useful to sb对某人来说是有用的；call sb给某人打电话。at any place在 任何地方。use sth to do用某物做某事。根据句意故选C。