Tāmen bìxū nǔlì ɡōnɡzuò.
他们必须努力工作。
They have to work hard.
Notes:
他们(tāmen): they
必须(bìxū):must, have to
努力(nǔlì): strive
工作(ɡōnɡzuò): to work
Example:
A:他们必须努力工作。
Tāmen bìxū nǔlì ɡōnɡzuò.
They have to work hard.
B:我们也是。
So do we.