Many environmentalists think that carbon dioxide is _______ for the global warming, which affects billions and billions of species across the globe.[ ]

Mr.Morse，who graduated from a famous medical university，spent years ______ his skills as a doctor.

I didn’t hear you because I _________the news on the radio.

I was_______ about it. I thought you were responsible and that’s why I scolded you. Please forgive me.

Energy drinks are not allowed in Australia but are brought in from New Zealand.[ ]