The global warming is more and more serious, for which human beings ______．

Where is your father ? －He is at work . He always has lots of work __________ .

I’m Mr. Brown from the police station. Could you tell me _____the butcher foundmoving slowly across the square?

________ of my sisters are experts in agriculture. Helping the farmers improve their farming techniques _________their duty.

I usually go to school_______ seven_______ the morning.[ ]