"Please cooperate with us."
Translation:Xin hãy hợp tác với chúng tôi.
This is one of the instances (sadly more common in these later lessons) where DL drops the ball by not giving us the hint for 'please' including 'xin hãy' leaving those of us without a desktop/laptop no choice but to learn this the hard way.
There's really not much I would change about DL, but this is definitely a good opportunity to improve. Why not at the very least give the learners a chance to rate the challenge of a sentence so we might at least get some warning before we make the same darn mistake every time? This is the toughest way to learn - why not make it a shred easier?