If someone has to an action or policy, they are responsible for it, and may be required to explain it to other people or be punished if it fails.
—These boxes are too heavy for him to carry.—Here, I’ll give you a hand________them.
I was on the point of going to bed ________ Mr. Zhang rang me up.
It’s really cold________July in Beijing now. Better put on your coat.
English is understood all over the world ________ Turkey is spoken by only a few people outside Turkey itself.
My little brother kicked the ball to the river; I took great trouble to get it________the river.