they have learnt English since three years ago.改为同义句____ three years ____ they started learning English.

问题描述:

they have learnt English since three years ago.改为同义句
____ three years ____ they started learning English.

it is three years since they started learning English.
it is+时间段+since从句是现在完成时的句式

About three years ago they started learning English

It's since

It's..since