1 . Citizens finally decided to write a letter to the mayor __________（涉及、关于） the problem of rubbish pollution. (根据汉语提示填空)

2 . _________ being the first human to walk on the moon, US astronaut Neil Armstrong’s life has been mostly unknown to the public.

A．Despite

B．Regarding

C．On account of

D．On behalf of

3 . —Are you going to invite Jack to our party?
—No, but he’s welcome to come along, ______ that he behaves himself.

A．concerning

B．considering

C．regarding

D．providing