Do you know when your friend ___ –I’m not sure. I will tell you when he _____

The rapidly growing birth rate brings about a lot of environment problems, which the government is supposed to take _____

I’m sorry that what I said just now has hurt you, but I didn’t do it _____

The air quality in the city, ________is shown in the report, has improved over the past two months.

Though _____ of the danger, he still went skating on the thin ice.