uphill

翻译：

It will be an uphill task for anyone to improve his or her IELTS grades from 6 to 8 in two months.

修改：To improve IELTS from Band 6 to Band 8 within two months is an uphill struggle/ task to anyone.

场景：在最开始的一段时间内， 不用手机是很难的。

例子： At the very beginning,  it can be an uphill task for us to put mobile phones out of touch.