When I turn aircraft the long way around:" EVA15 it will be a left turn on course today, turn left heading 180". I also only give the non English types one instruction at a time. May take a few extra transmissions but you save time not having them asking to confirm something or a long winded reply. With the US not being responsible for errors in read backs, I sometimes wonder if they pay attention or if they are already onto the next task in their mind. And did I hear correctly she assigned an altitude with a frequency change and didn't receive a read back? Seemed like an accident/incident waiting to happen.