Where is your manager?—Sorry, he is ____ for my company.[ ]

Is this the first time you _____Chengdu ?—-No. But the first time I _____here, the city wasn’t so beautiful.

She is the only one of the girls in our class______ been to the United States.

I on my way here and had to ask the police for help.

He doesn’t know_________ the work by himself.